personally i dont think its going to work. here are a few reasons why
1) you can still get music for free from various p2p programmes. so why are most people going to bother paying for something which they can do for free.

2) It doesnt work out that much cheaper than buying cds, it still costs around £9 for an album on napster (according to sky news). If you buy a cd you have a higher quality sound and a nice case/artwork, rather than if you downloaded a song (a relative poor quality recording, 128?) then ripped that onto a poor quality cd with some crappy case. also you'll have to buy cds.

3)im assuming that the files are locked mp3's. that is once you put them onto and ipod/creative player, then you cant extract them off again. so for example you download tracks, put them on your ipod then delete them off your computer. it is not then possible to get them off your ipod back onto your computer. (as i found out when i payed for a download off a site, now that download is stuck on my mp3 players)

other issues may include the amount of tracks available to download, and the nature of those tracks. so there may not be obscure music or quirky covers from popular bands or rare/unreleased stuff. again why are people going to pay for something that doesn't have all the tracks they want available.

does anyone think its going to work?
i may curb illegal downloading a small amount, but i dont think it will significantly.