The Saffire by Focusrite is an amazing piece of kit. I'm using it in my PC I have for recording.
http://www.focusrite.com/productdetails.asp?id=38&iRange=5

My gaming PC has the Creative's Sound Blaster X-Fi Elite Pro card which is also very good for music and games sound amazing, if you like to play the odd one.

Shop around there's loads out there.