have you read my two very long post jrecee???
if you have a computer alrady, all you need is a video card which you should have inferred from my post. And not even a super fly one, you can pick up a cheapy Nvidia card with DVI out for like 50 bucks on newegg. As long as you have any PC around with enough power to run an emulator, and any Nvidia vid card with DVI out, then you're set to go.
Oh and if you by a new HDTV... like you said you wanted to... VGA is still always an option as a lot of HDTVs come with VGA in as well (it's how I play my Dreamcast on my HDTV).
It appears though you keep looking at prebuilt PCs from local best buys, circuit city, or even dell. These ARE NOT going to be cheap for what you want as they aren't really geared towards what you want.
If you need a computer (because say you don't have anything sitting around) I'd suggest checking out newegg, looking for a simple barebone kit, a processor, and a cheap Nvidia video card. Put it all together, and run! Shit you can do this for pennies on the dollar. I'm talking like 300 bucks or less. Ain't like you need cutting edge.
for instance check this little bad boy:
http://www.newegg.com/Product/Product.a ... 6856158007
comes pretty much built with a cpu, hdmi, hard drive, all kinds of goodies for 350 bucks. More powerful then the computer you just poted in the last post.
My point is you can go there and find all kinds of machines. I found a Atom 270 for 80 dollars. You have to get a hard drive and OS yourself and it doesn't have DVI... but 80 bucks!?
http://www.newegg.com/Product/Product.a ... 6856119011
shit toss in a 30 dollar hdd and Linux and you have a pretty nice little media thin client (as long as you have a VGA display).
OH and to warn you... just because you can get a computer that outputs HDMI or DVI to an HDTV with high resolution. Depending the TV you will still have some level of "fuzziness" to the icons and text. Televisions are optimized for colour and visual emerssion... and not for text and fine stuff like that. LCD will give you the best result probably, but still it isn't the same as a REAL computer monitor which is built with text and the sort in mind.