|  On a PVR I would disable a lot of stuff, that wasn't needed for that function.  Probably not put in networking, so security updates would not be needed.  There are Myth based versions, so maybe put on one of those.

Yep, in that sense I'm an old dog learning new tricks, for a faster booting machine I'm learning how to use nLite, an acquaintance of mine says I can get 2000 down to 93 Mb, rather than the 4-8gigs it usually takes up,slightly more for XP, just by removing unneeded services. I just never did that before as one machine serves as a backup for the other so I don't lose internet access. Then there's vLite for Vista and W7. The point is if you can afford to make each machine single purpose, then you can strip alot off and just keep what's essential to run the tuner(s) and recording/timeshifting apps.
That way if the power goes out while you're not at home, it'll reboot itself more dependably or if during a recording session away you might only lose 30,20 or maybe even just 10 seconds of material, depending how fast the app relaunches and reads it's recording schedule, part of which should be already in the registry before the reboot.
Right now I can lose up to two minutes because of the upgrades make both bloated.
I hear Myth works great with the HD Homerun, though keep the RJ45 jack active, because you may want to connect once a week for the Program Guide[s]...Zaptoit or Schedules Direct and sync your clock with the NIST time servers. That's the only reason I like the Motorola portable modem....looks like a pie slice sitting on its wider edge.