Re: Build a PVR
 

Try googling BeyondTV (I'm too lazy to link it). I have it on my system (ATI theater 550pro for the card bit). Works excellently. It is somewhat expensive though but you don't have to pay for the guide after you've bought the software.

There's also a free option that I tried a while ago but found it too clunky. It may be better now though. http://www.gbpvr.com/

Re: Build a PVR
 

The other windows program I know of is Sage TV, or something like that.