Jason,
I hope the wall isn't up yet...
If you have the option to pull more cables I would. Go with in-wall rated cables(
www.monoprice.com has the best prices around and have used them exclusively) - Standard RCA composite (go with a 3 wire yellow, red, white) for other options later on if needed you never know,
component (red,blue,green, and audio red,white),1/4" stereo audio (for audio or IR repeaters) optical cable,VGA/DVI, and USB (great for IR repeaters from your computer and hooking up Xbox accessory items), and a pull string in a conduit(make sure you have firestop on both ends for code purposes) for pulling up additional cables later on and when you pull a cable, pull another string. Oh yeah go with in wall rated
HDMI v1.3a with ferrite cores too
Put your power in a clock box(it is recessed into the wall so all your plugs won't stick out -great for a surge surpressor to protect your TV- the Belkin portable one works well) and if possible you can terminate the cables to a nice wallplate (
Monprice sells them too) for a neater install if you want to, but adds to the cost about $10 and the amount of cables needed.
Monoprice also has some nice wall mounts for around $55 and under. I went with a 15 degree up/down tiltable wall mount that allows for 40 degree of swing in the left and right direction as well as mounting flush to the wall. It also can be pulled away from the wall about 5"-11". It literally took less than 10 minutes to install to the studs (most of it was taken measuring the optimal height and location). Good way to do it is get a piece of cardboard that is the same size of the television, mark off the VESA mounting screw locations for your mounting bracket, and tape it to the wall with painters tape to see if that the height and location is good for you then make a template for your mount location with the cardboard positioned and drill your holes where your studs are.
Remember most PCs will only allow either digital out or analog out and not both. So you will have digital audio to the TV only. If you plan on adding a receiver for video switching make sure it can upconvert analog sources to digital if you have them and the other way around (down convert) if you plan on using audio zones most receivers are analog only.
On the PC side of things, consider power and price point, expandability. The current price of laptops makes for lower power requirements, quiet options for home theater PCs. Especially using network based tuners like
HD Home Run and laptops with full HDMI out, like the ones from HP or you could use a separate DVI to HDMI connector and audio cable. Shuttle cases and others like Zalman,Silverstone,Origien, all allow for expandability and lower power options may work as well. The nicest stand alone option for a small low power MCE PC is the
MiniMCE for $499, but I don't think it will fit this installment.
Good Luck and keep us informed!