Reply #3: If your goal is MP3, then one of the inexpensive USB turntables will suffice.

[Fire Walk With Me]

If you want CD quality or above (some soundcards support 24 bit/96 KHz rates, and 24 bit, even at a 44.1 sample rate, is vastly superior to 16 bit, much less MP3), use an existing turntable (as the above poster recommended) or get something like a Music Hall turntable ($500-ish), a good preamp and soundcard, and go to town.