The PC Pro office is agog this afternoon. We’ve stumbled across Spotify – a genuinely free, legal music service that gives you unlimited streams of pretty much any track or album you can think of from the big four music labels and we’re all left wondering: what’s the catch?

All you have to do is register with the site (use this link, don’t go through the homepage, or else your name will simply be added to the waiting list) and download the desktop software, which is a mere 1.5MB.

Once installed, you’ll be presented with a piece of software that looks so similar to iTunes, I’d be amazed if Apple’s lawyers aren’t already ordering Havana cigars in anticipation. Pop the name of any band, track or album into the search box, and you’ll be presented with an impressive list of matching tracks, any of which can be played almost instantaneously with a double-click. Others can be added to the queue with a right-click. 

There doesn’t seem to be any limit to the amount of times you can listen to a song – whole albums are seemingly up for grabs. Like iTunes itself, Spotify has struck deals with all the major record labels, and the only missing mainstream albums are the usual hold-outs: The Beatles, Pink Floyd, The Grumbleweeds.

So how the Charlie Dickens are they making this pay? Every 20 minutes or so, in between tracks, you get hit with a short advert. So far, I’ve had Moira Stewart reminding me to get my tax return in on time and a reminder about claiming child benefit. Literally taking with one hand and giving with the other. 

Spotify offers day passes for 99p or monthly subscriptions for £9.99 if you want to avoid the ads and pick up a few extra features. Nothing worth paying for, in my opinion, so I’m hoping the Government advertising is enough to keep this brilliant service in the black.

One word of caution: delve into the preferences menu and you’ll see that Spotify creates a local cache. It’s set to steal no more than 10% of your free disk space, but you can reduce that quota if you wish. And before you go hunting out that cache in anticipation of a shedload of free MP3s being stored on your PC, forget it: we’ve already looked, and they weren’t that naive.

And for those of who you who read my blog post from yesterday – I’ve now found something to stick on my spare screen!