I'm going the PC route myself, but for some reasons that might be different than what others would do it for.
Basically, I have 2 PCs hidden in the livingroom (the one under the corner table is the file server with 2TB of HD space, and the one hidden behind the couch is called "livingroom" on the home network and is essentially the entertainment center). I use this route basically because I don't watch actual TV (no cable/sat tv hookup) so I am content with just internet content and the stuff on my fileserver (almost full BTW).
The livingroom PC I have isnt hooked to a TV, but a decent sized monitor. I got a remote for it tho, which works excellent for controlling BSplayer (BSplayer has the best configuration for remote controlling I have ever seen, including using something like oh say... a minipac or keywiz to control every aspect of it (including what key opens the "about" window for the program))
If I ever do get a TV hookup, I will just get a capture card for the livingroom PC and use either a computer monitor or a TV out card for the display.
As per you, I would recommend using a PC for a few simple reasons (that are different for me going to that option):
1. Pc's can be configured and parts can be harvested/exchanged over decades (less chance of obsolesence)
2. Pc software for handling DVR/internet/etc tends to be better and may "last longer" (see #1)
3. Pc's are cheap (or free in many of my cases [NO! I didn't lift them! They were given to me!]) and wont tie up your game console for that use (In case you want to use both services (internet TV and gaming) at the same time, with a PC setup, you can move the console to another screen/room without disrupting the system you have setup for TV)
Anyways, just my ramblings, take what you can from them.
ps. The cost of my entire fileserver and livingroom entertainment center systems was $ 310 (120x2=240 for 2 1TB external drives + 45 for a computer remote + 20 for ethernet cable + 5 for a CR2032 bios battery) Everything else was either given or harvested from older stuff I had.