I got a tip as well, you go to this website:

http://www.kpm.co.uk/

That's KPM Music, they're a production music library, you know, library music? Lot of people have sampled KPM stuff and the likes (De Wolfe (another production music company)).

This kind of music is licensed to movies, commercials, etc. And you have to be approved to be able to download anything.

BUT.

You can register a free account, and that gives you access to listen to A LOT of material (have to have Realplayer installed), now all you have to do is use an application like Audition (previously called CoolEdit), Wavelab, SoundForge, etc. And record what you're listening to. Most soundcards support a record "What U Hear" feature, it's find in your sound device mixing controls. Start button -> Control Panel -> Sound, etc.

You'll have access to literally thousands of hours of music this way. You can browse different genres, and music from different production companies on this website.