Hello BassPlayer!
I started hardisc-recording not so long ago and had the same questions. The basic components (beside the motherboard and a cpu as fast as you can get) are 2 harddisc-drives (choose the quick ones as ultra-dma, one for OS and the other for audio-data), a cd-burning-device and of course the soundcard.
If you're recording alone, you can do well with a standart stereo-in/out-one for the first, if you need more inputs (~8 ins and outs) you'll find lots of info in equivalent posts, look around.
Depends on what you wanna do.....
Also, if you use one comp for multimedia/audio recording it's nice to install two OS, so you can "tune" your audiosystem right for recording and no anti-virus-stuff and all the shit coming with windows (that you actually will never want to need) can be turned off and won't disturb your audio anymore.
There's a free version of ProTools (digidesign.com) that offers 8 audio-track an lots of midi. I use cubase and I like it, but whoever uses another programm probably likes it too, so try to get demos of any program that seems to be working good with you before u buy one (........)
And: buy your hardware now! Why? Take a look at this:
http://www.againsttcpa.com/news.html
Good luck!
ag