How big a hard drive is needed for say 30 hours of recording? Where can I get the necessary software and hardware? I'm computer illiterate. In that case, I'd suggest you buy a Tivo. Getting good A/V results from a PC isn't for a computer illiterate. I'm using a Home Theater PC to drive a video projector and surround sound, am very computer literate, and it just isn't that easy to get this stuff all working right.
If you really want to go down that path, there are people who sell pre-configured HTPC's, but a Tivo would be much cheaper just to get the PVR functionality.
BTW, a great way to learn a lot about this stuff is at the
AV Sciences Ultimate Forum. There are many knowledgeable users, a good sprinkling of industry people, good FAQ's around, etc. Tivos and PVR's in general are covered in the forums labeled "Digital Video & Audio Devices", about 3/4ths of the way down the page.