CNET has posted a guide to choosing PVRs. Their questions boil down to "Does your cable or satellite provider offer a free or discounted DVR?", "Do you need high-def recording?", "Are you willing to pay a premium for the real TiVo?" and "Do you want to archive your recordings to DVD?" I'm going to keep this link around for the next time someone asks me which PVR is right for them; copying and pasting is a lot easier on me than careful consideration of a person's unique needs.