Thomas Hawk recently posted his interview with Windows Media Center bloggers, which is an interesting insight for people like me who don't really keep up with Microsoft's offerings. One thing I liked was that the developers have pinpointed the most important litmus test for PVRs:
Speaking of wives, there’s something what we call internally here at Microsoft the "SAF"- Spousal Acceptance Factor. It’s a very important informal metric we use internally just like the "eating our own dogfood" metric where we take builds home to test in addition to formal betas and usability testing.