As I've noted in another thread around here, hardware for a home-brew PVR is pretty simple these days. An Ion2 "nettop" (eg. Zotac HD-ID11), plus a 1GB RAM stick, plus a 2.5" notebook style hard disk, and you're almost there for about $250 or so.

Add a $10 remote control w/receiver (DX), and then think about a capture device. As Bruno points out, the HD-PVR USB box can capture high-quality video from the component output of a sat receiver, and pretty much any USB DVB-T/DVB-S device ($50-$100) can capture from composite (and sometimes svideo) outputs.

SageTV, MythTV, GB-PVR, MS MCE, etc.. provide the software. The challenge is to pick one that also has a way to get the EPG ("program guide") data for your specific sat provider.

Cheers