First question is what do you want an HTPC?
Second, your system is WAAAAAY too complicated and limited in functionality.
This is what we have for the "whole house DVR":
a) HTPC wunning Windows Media Center connected to the AVR and TV in the Family room controlled with a remote.
b) 5 Media Center Extenders on the network connected to 5 TV's controlled with individual remotes.
c) 10 total tuners (6x CableCard for encrypted and copyright protected cable) and 4x ATSC for OTA channels on the network.
d) 20 Tb RAID array on the network.
End result: Each TV can view content independant from the others. Each TV is a DVR, capable of recording, pausing, rewinding and fast forwarding live TV, and viewing recorded TV programs, as well as movies from the digital collection, play music, and so forth.
Recording schedule is storage (TV, movies, music, etc) are shared and unified. One can pause/stop in one room, and continue from that spot in another.
No IR blasters, not repeaters, no multiple audio wires, speakers, etc. Just a Cat5e wire and 24 port switch. Other computers are on the wired network, as well as 5 routers turned into access points to give 100% wi-fi coverage for the wireless devices.
IP cams are used as a baby monitors (or security cameras) that can be picked up on any wireless device (iphone, android phone, iPad, ePad, laptops) or wired devices (HTPC, other PC's) in the house, or when needed outside access is granted too.
Try getting multiple TV's on with any provider, and you will be hit with multi-box rental fees, add DVR for another fee. This set up only cost $3.99/month to rent a single CableCard. And trust me, if you think 2 tuners in a DVR is enough, we thought 2 was enough until we got 4, then 8, and now 10. Same with storage. 4 Tb may be enough initially, but we are running out of room on the 20 Tb array.
6 TV's in the house on FiOS and we only pay $4.99/month to connect them all!!! Power to the CableCard and WMC7!!!