I'm not sure that I agree that a $99 purchase constitutes a "relationship". OP can try both BTV and Sage for free. Either one will turn his older Athlon X2 with XP into a very decent PVR for OTA and SD cable. That's all he wants, at least for now. From experience I know that BTV is easier to set up for a newb. Out of the box, with no additional software or downloading of addons, BTV will mark and skip commercials (called Smartskip), compress mpeg recordings to an h264 divx profile that can be played on cellphones etc (called Showsqueeze) and allow you to play and watch BTV on a client PC with BTV Link ($20). Of course Sage can do all this and much more, but with the extra functionality comes complexity.
we have not heard from OP for a while, maybe he is busy test driving ;-)
I have a tuner on order so once I slap it in I will play with SageTV and see how that chugs along. My XP box is MCE (if I remember right) so there are probably some tuner services I can turn on and play with. That will be my first order of business.
I just bought a new TV that almost (but not quite) makes a Media front end obsolete with it's DLNA client and internet access so whatever gets the recording job done with the least CPU cycles will win.
Thanks so much for all of the replies, it's great to see that the debate rages on ten years later This is why I bought my poor ole' dusty Replays to start with.