Well for starters you need somekind of A/D converter, M-audio makes a bunch including the inexpensive midiman...you'll need software to record your music, Cakewalk sells budget versions of their Home Studio that get the job done...these would be products for basic hobbyist home recording. You can move up to MOTU Firewire support and Cakewalk Sonar...but the cost is much more. Check out the websites for M-Audio @ www.midiman.net
and Cakewalk @ www.cakewalk.com
. There is a ton of product info at these sites. Check out www.pcmus.com
for much more info regarding Digital recording. Good Luck!