Here’s something that’s crept up on us at PC Pro towers: Windows 7 has overtaken Windows XP as the operating system most used by visitors to our website (click graph to enlarge).

The graph above runs from January 2008 until the end of last month – Windows 7 actually surpassed XP for the first time in December, we just hadn’t noticed it before (we’ve been busy, OK?).

The growth of Windows 7 has been quite extraordinary. In a little over 18 months, it’s gone from nowhere to the most used operating system. Compare that to Windows Vista, which didn’t even come close to toppling Windows XP, never getting any higher than 27% of the PC Pro audience.

It’s also worth noting the gradual incline of Mac OS X, which was used by 4.8% of our visitors at the beginning of 2008, and has since more than doubled that to 12.3% last month.

And what of Linux OSes? Our stats software only allows us to plot four trend lines at a time, hence the omission of Linux from the graph. Yet, it’s surpassed our Apple-flavoured friend in terms of growth, accounting for a mere 2.4% of visitors in January 2008, and 6.7% in February 2011.

That’s nigh on a fifth of the PC Pro readership using a non-Windows OS. Times really are changing.

Update at 5pm:

A couple of the commenters below asked for the figures on iOS and Android. It appears our regular stats software doesn’t discriminate between Mac OS X on the desktop and iPhone/iPad/iPods. Likewise, the Linux figure was indeed bolstered by Android users.

Google analytics provides a much more detailed breakdown of operating systems, although there’s a slight variation in the figures because of differences in the way the two analytics packages count users.

Here’s the top ten for visitors to PC Pro for February 2011, as provided by Google Analytics:

1. Windows 83.08%

2. Macintosh 7.31%

3. Linux 3.09%

4. iPhone 2.96%

5. Android 1.68%

6. iPad 0.91%

7. Unrecorded 0.51%

8. iPod 0.22%

9. BlackBerry 0.09%

10. Symbian 0.04%

With the arrival last month of Ubuntu 10.10 Netbook Edition, it’s time to revisit a familiar question: which operating system is best for a netbook? Linux-based systems may seem well-suited to lightweight devices (the original Asus Eee PC ran Xandros Linux), but there are advantages to the familiar interface and applications of Windows.

Indeed, if you buy a netbook today it will probably come with Windows 7 Starter, while older models are likely to be running Windows XP. Still, it’s easy to move from either to Ubuntu Netbook Edition, and of course it’s free. If you want to upgrade an older netbook to Windows 7 you’ll have to shell out £65 for the Home Premium edition, as Starter isn’t sold separately.

Each of these four operating systems has its attractions, but the key question is how each one performs on low-powered netbook hardware. To find the answer, I’ve spent the past few days installing them all – Windows XP Home, Windows 7 Starter, Windows 7 Home Premium and Ubuntu 10.10 Netbook Edition, with all available updates – on an Asus Eee PC 1008HA, and timing a series of typical netbook tasks to discover which OS makes the most of lightweight hardware.

Test 1: Starting up and suspending

Nobody wants to wait around for their netbook to start up, or to wake from sleep. Happily, suspend and resume worked perfectly on all four operating systems, so I was able to time how many seconds each took to sleep and resume from an idle desktop, along with boot times from cold.

As you can see, I tested Windows 7 Home Premium with both the Basic theme and the standard Aero theme. For this exercise it doesn’t make much difference, but I suspected it might on later tests.

Result: Windows 7 is slower to boot than XP or Ubuntu, and the Home Premium edition, with its full complement of services and features, is the slowest OS. However, most of the time we expect you’ll be resuming a netbook from sleep, and here it’s effectively a three-way tie, with XP only a few seconds slower than the rest.

Test 2: Opening applications

For this test I used the latest version of OpenOffice.Org on all platforms (with the “Quickstarter” disabled) and opened the applications by double-clicking on a .DOC file and a .XLS file that had been copied to the local desktop. I opened each file twice, to get a measure of how quickly the applications were able to launch both from cold and once cached.

Result: Windows XP was clearly the fastest OS at opening and reopening applications, while Windows 7 Home Premium did poorly, especially with Aero screen composition disabled. Interestingly, Windows 7 Starter scored a consistent second place, while Ubuntu failed to distinguish itself.

Test 3: Web performance

For this test I loaded a variety of JavaScript- and CSS-heavy web pages into the latest version of Google Chrome and used the browser’s built-in monitoring tool to time how long each one took to render.

Result: Given the timescales we’re dealing with (that Y axis is in seconds), this is essentially a draw, though enabling Aero seems to have a deleterious effect on Windows 7 Home Premium — strangely, the opposite to the effect observed in the applications test.

Test 4: Flash benchmark

To test Flash performance I used the free Flash Benchmark 2008 by Snails Animation, using the latest version of Flash available within Chrome. None of the platforms was able to get further than the medium-detail test. This graph measures frames per second, so taller bars are better.

Result: Aero seems to knock a few per cent off Flash performance, but it’s clearly Ubuntu that fares worst. Linux users have long grumbled about second-class Flash support, and these scores illustrate their point.

Test 5: Video performance

WMV and MPEG4 video files at resolutions up to 720p played perfectly well “out of the box” under all operating systems. However, none of the operating systems could cope with HD files from either YouTube or BBC iPlayer — in all cases the framerate dropped to only a few frames per second, making videos wholly unwatchable.

Result: Ubuntu’s poor Flash performance seems to drag it down in iPlayer: in windowed mode, video was slightly jerky, and in full screen mode it was too juddery to enjoy. The YouTube player seems to suit Ubuntu, though, while visiting the same site in Windows 7 caused videos to stutter too much for comfort.

Conclusion

There’s no reason not to give Ubuntu’s latest Netbook Edition a try — after all, it’s free, and it’ll run direct from a USB flash drive or coexist with your existing OS. The simple Unity interface is arguably better-suited to a basic netbook role than either the dated XP interface or the feature-rich Windows 7 front end.

For basic web and productivity tasks, Ubuntu’s performance appears no better than Windows, and for online video and games it’s distinctly worse. So while Ubuntu gains marks for openness and simplicity, there are still good reasons to hang on to Windows, at least until Adobe gets Flash up to speed.

If you’re currently running XP, though, it’s probably not worth paying for an upgrade to Windows 7 Home Premium: that OS isn’t designed for low-power devices, and it gave wayward performance in several of our tests. XP proved a stronger performer overall, and was the only OS to give a good experience across the iPlayer and YouTube tests. The interface is showing its age, but if that bothers you you can dual-boot Ubuntu and get the best of both worlds.

If, on the other hand, you’re shopping for a new netbook, Windows 7 Starter isn’t a bad deal. It’s not very customisable (for example, you can’t change the desktop wallpaper) and it doesn’t include any goodies such as Media Center or encryption tools; but its comparatively light weight lets it boot and open applications more quickly than Home Premium. Nor is Windows 7 as nippy as XP, but from an overall performance perspective the Starter edition’s as good as Ubuntu, and better with Flash content. By all means test-drive Ubuntu, but the truth is that no OS will magically turbo-charge your netbook.

It’s so well regarded that some of the less well-written printer drivers suggest that you run it to clear up their mess when in the midst of a version upgrade. It’s also the proud holder of PC Pro’s Software of the Year 2008 award.

I am blogging this because Piriform commits a couple of very minor sins in the setup of the utility. One is that it tries to sneak the Yahoo toolbar in on you, unless you know to always untick the check-box; the other is that it’s king of the ultra-tiny version update. Only Winamp is worse, in my experience – hardly a week goes by without a new release, during which a moment’s inattention will land you back with the toolbar.

This may seem obsessive but I can’t be the only person who has seen people browsing on netbooks with upwards of six toolbars in Internet Explorer, and left with a browser window able to show about ten lines of text.

Anyway, Piriform has released a major update to CCleaner. It’s now on 2.22 and there’s support for cleaning out the Google Chrome cache and the Sun Java cache; just these two tricks alone are worth the clicks to get it.

Yesterday, I came across a box that I had only given a cursory glance to before: the Preferred Networks settings, which can be found by clicking on Change Advanced Settings from your list of available wireless networks in Windows XP.

Stored in here was a list of all the wireless networks I’d hooked on to since I’ve had my laptop. The Wi-Fi hotspot at McCarran airport in Las Vegas used when I covered CES in January (OK, we do get a bit of glamour), the Pro Labs connection, the guest network at Microsoft’s offices. Anyone who rifled through my laptop would have a pretty good idea of where I’ve been for the past year. And what if a suspicious spouse stumbled across it and found a Wi-Fi hotspot at a hotel he/she didn’t remember you mentioning before?

How long before Windows is responsible for the first Wi-Fi divorce? I’ll give it six months.