If you don't mind snap, crackle and pop with your music, then recording via a soundcard is OK. However, most soundcards (even the expensive, high-end ones) are optimised for output NOT input and the results can be decidedly grainy.

If your budget can stretch that far I would recommend buying an audio input device - I use a Tascam US-122 USB device, though there is no shortage of alternatives. It just plugs into (and is powered by) the computer's USB port. The results are far superior. The Tascam comes bundled with Cubase recording software.

http://www.tascam.com/Products/US-122.html

Hope this helps.