Now that Microsoft’s done away with those silly E versions and decided to offer upgrade versions of Windows 7 in the UK, you might be wondering what versions of Windows can and can’t be upgraded.

Fortunately, Microsoft has produced a chart to show you what’s possible (click to enlarge):

Fetched your paracetamol, yet?

The chart confirms what we’ve known for a while: that XP owners can essentially go whistle for an upgrade, and that they have to start from scratch with a clean install.

However, even those who shelled out for Vista aren’t necessarily able to upgrade to the version of their choice. Those who paid through the nose for Vista Ultimate are particularly hard done by, with their upgrade options restricted to Windows 7 Ultimate, providing a final kick in the teeth for buyers who were promised plenty of “Ultimate Extras” and received absolutely nothing of note.

Even though the upgrade path has now been opened, I’d still echo Jon Honeyball’s earlier advice and recommend that everyone undertakes a clean install. Not only does this give you the freedom to choose whichever version of Windows 7 you want (including the 64-bit options), it also means there’s no chance of detritus from Vista being carried over into your Windows 7 installation and slowing down the PC.

(P.S. As Jon Honeyball, and the ever-vigilant David Wright points out on comments below, did Microsoft even launch a 64-bit version of Vista Starter, as displayed in the grid? Although there are Far Eastern sites on the web claiming to sell it, Microsoft’s own site makes no mention of it.)