I am using MythTV as a PVR (think TiVo). I have included here a bit of information about it.
The whole lot runs off an Athlon XP 2000+, with a Hauppauge WinTV/PCI card.
The TV is driven directly off the onboard VGA output (S3 ProSavage) using a VGA to SCART converter. This drives the RGB input of the TV at native PAL resolution using some custom modelines in X.
The RGB output from my Sky Digibox is connected to my VGA to S-Video converter, which is connected to the S-Video input on the TV card.
MythTV is controlled by an infrared receiver driven by LIRC, and it can also control my Panasonic Sky Digibox through an infrared LED.