Doesn't your soundcard have an analog input? The soundcard will have an on-board ADC (analog to digital convertor). If it has a sub miniature jack that takes a microphone you should be able to buy a (sub min jack to RCA phono's) cable that you can use between one of your pre-amp tape outputs and sound card, the turntable going to the regular phono input. Radio Shack should have them. $10 max?
Digitizing from vinyl?
Is there a reasonable way to transfer music from vinyl to CD's for use in the car and/or a portable CD player? I've got a couple of decades of records and most of the good stuff I've bought on CD, as well, but I'd like to have the convenience of CD's for some of the more obscure recordings. I've got a CD burner available but don't know what should go between the turntable and the computer to do the analog to digital conversion. I'd be willing to spend a few hundred dollars if it's possible to do it for that kind of money. Thanks