If you are running the SageTV server on your WHS, I would recommened installing your bluray drive in the server as you can add the drive as an import path and then the disc than becomes availalbe to any of your SageTV clients (assuming AnyDVDHD is running).
If you are not using the client to run comskip or showanlayzer for commercial skipping, you could save some money by going with an Athlon X2 instead of the x4. And to save costs even more, have you looked at the HD300 to see if it will meet your needs? It handles bluray playback (unencrypted) and hd tv, is extremely easy to install/setup, and is silent.
