Another thing that I think gets people confused is the HDMI = HDCP thing, this is simply not true. HDCP will depend on your source, HDMI is mearly DVI video and SPDIF audio in a single cable.
I too use SageTV but I don't rip the disks, I encode from a megachanger.
I also use AnyDVD to play disks directly from the drive to the client, this covers DVD, HD-DVD and Blu Ray.
I also use PCs for HD clients and the MVPs for SD clients, both need only a Cat5 cable. The PC client is limited by your knowledge/imagination and the MVP has the same GUI found on the server/clients. I like PCs for HD as they allow for web surfing while watching, also they provide for a local disk drive and more options when it comes to remote controls. The HD extender should be more stable and consumes much less power.