@St. Jude
Ditto to everything. In fact, I'm taking a course in popular music as an elective right now, so I'm discovering all the 'classic' rock I wasn't familiar with before (The Beatles, Pink Floyd, etc.). Nevertheless, I too realize that it is ultimately unhealthy for the mind and soul, so I still stick to classical and church music for the most part, interspersed with some jazz and folk music.
Also, not to sound like an advertisement, but if you enjoy classical music, I highly recommend trying eMusic. Unlike iTunes, they use a subscription service, so you pay a monthly fee and get an allotted number of downloads, but even if you cancel you get to keep your downloads since there's no DRM involved. There's even a trial where you can get 100 free downloads, so you can cancel within the first month and keep all your free mp3s!
http://www.emusic.com/promo/new100free/index.htmlI've been going through the site recently and have been astonished at some of the bargains that can be had. The per track cost generally ranges from $0.30-$0.40, depending on what subscription plan you choose, and the length of tracks makes no difference whatsoever. Hence, an hour-long track costs the same one download as a 30-second track. Since most symphonies, concertos, string quartets, etc. are four tracks long, a 60+ minute symphony, for example, only costs between $1.20-$1.60. Pretty crazy, at least from a business perspective.
Other than that, internet radio is always a good source of free music, although they do tend to play the same popular pieces over and over.