You'll have to set out in a way what you want first before deciding on the final configuaration of your hardware and software.
For starters your PC is good. But you'll need a separate hard disk for the software to use as a "scratchpad" where it keeps its temp files. The audio software and the scratchpad must not be on the same hard disk, it will definitely cause latency issues. If you intend to lay down just one stereo track at a time, a mid to high end commercial soundcard will suffice. Minimum should be at least an SB Vibra, with SB Live and Audigy being the better choices. If you intend to lay two or more tracks simultaneously (e.g. different tracks for different parts of a drum kit) then you'll have to get a multi-track soundcard.
Then you'll need a mixer, possibly two if you intend to use two or more simultaneous tracks. My own home studio, I just used a 4-input China powered mixer which also doubles as the vocals amp. Use that as the preamp because if you use the mic made for computers, it may sound real [gooey brown stuff] (noisy and too sensitive). Not to mention that you'll be limited to only one mic.
Then the software. If you buy say an m-audio soundcard, it may come with Protools M-powered software, which to say, are made for each other. Bar that, there are good software around like Cubase, Adobe Audition (my setup) and Cakewalk Sonar XP.
Then read up on miking and mixing techniques. Beauty of software controlled is that you can "pre-program" many things like fade-ins and fade-outs, panning etc. On low end analog setups, you will have to do that manually as the mix is going on. Beauty too of software is that you won't need too many, if at all, outboard effects. Almost everything you will need is in software : compression, delay, reverb, chorus even distortion. Nice thing is you can always "undo" whatever you did
. Right now the only outboard effect that I wish I had is a Compressor for the drums.
BAMF
