Any generic receiver should be easy to repurpose as a phono pre-amp. Phono in, tape out. For ripping vinyl myself, I've got a borrowed turntable, a Radio Shack "Disco DJ" mixer, and an Onkyo USB external audio card. If you want to have a lower noise floor, the external USB devices are the way to go because you don't have all the electrical noise inside your computer messing with your sound.

If you're using a Soundblaster, be careful what resolution you're digitizing at. I think Soundblaster's only run natively at 48KHz. If you ask them for something else, they first sample at 48KHz and then digitally resample. You want the original 48KHz data to feed to your MP3 encoder (assuming you can tell it that you're giving it 48KHz data rather than the usual 44.1KHz data).