If you have an old record deck, then I would suggest simply using that with a high gain amplifier (which can be bought as small boxes for a small fee from Maplins or such places). Connect the output from that to the analogue in port on your sound card and record using some sound recording software (obviously at a a suitable sampling rate - generally 44.1kHz).
From my experience of doing this a few years ago, the major problem was finding some way of removing the clicks that appear from the vinyl source. I never found any decent software that removed them satisfactorally and often went through manually reducing the volume at the click point for the worst offenders.
As far as USB turntables go, personally I have had no experience of them. However, people I know have used them and been disappointed as the quality of the turntable has been low and they haven't lasted very long.
Hope this helps.
Rhapsody