Well I disagree on the raid, it adds a lot of cost, a radical amount of complexity a lot of the time, and MAYBE it's implemented correctly in both software and hardware.
16 gigs of RAM
256gb SSD drive (if you need more space pick up a 2 tb drive to be a second drive and to back up the shows, etc on the first drive and have a box.com or dropbox account for the off site backup)
i7 like Steve said
Your video card will not be as big of a deal, something in the mid-range will be lovely as those TV's only handle 1080 vertical lines as that is all 1080p is.
You might be able to pick up some water cooling equipment reasonable to make the computer even quieter, but honestly my i5 pc with 16 gigs and a hybrid disk drive is completely silent.
I like good sound on a computer, so look for a MB with a higher quality audio section, LOTS of 3.0 USB ports
gigabit lan connector, unless you are totally wireless.
I second Newegg.com and have bought from tigerdirect.com as well.