I use Sonar and a Firepod, but really, I'd recommend you try out computer based recording first. I know a lot of guys that just can't seem to 'get it'.
You can pick up an interface on the cheap (just a single in M Audio runs like $100), and try out a few trial versions of software (Sonar, ProTools, etc.) and see what you think. Then you can decide if it's worth your money to get something really nice. It will also give you a chance to try out different DAWs, as some people prefer one to another.
I've been using a computer to record for about 12 years, so if you have any in depth questions, feel free to shoot me a PM.
Alex