Take a look at mythtv.org. That's a pretty sweet software based PVR that I'm going to install as soon as I can figure out how to control my DishNetwork receiver with an IR transmitter (just like the TiVo does?).

later,
ajay

PS. Look at those screenshots! They just added the 'edit' abilities so you can edit out the commercials before you burn the shows to VCD/DVD/etc...