WHS 2011 build advice

[Dos101]

Hey guys, I need some advice on my home server build. Currently I am running Windows Home Server 2011 RC (soon to be the RTM version) on a system with the following specs:

E2180 @ 2.8GHz
Asus P5Q Deluxe
4GB DDR2 800MHz
250GB HDD (OS)
2x 1TB HDD (movies, pictures etc.)
Silverstone OP750W

I use PS3 Media Server to stream content to my PS3. It works very well most things but for 1080p content I experience a lot of stuttering. So to prevent that I installed PS3 Media Server on my second desktop (Athlon II x4 630, 4GB DDR2 RAM, Asus M3A78-EM, Sapphire HD4670 512MB, Corsair VX 550W), and mapped a drive to the location of my movies on the server so PS3 media server could see it.

I just moved into a new place and my second desktop will be using wireless as opposed to a wired connection so I decided this would be a good time to upgrade my server and second desktop, and to just install PS3 Media Server on the server itself.

At a local computer store I can get a Gigabyte GA-880GM-UD2H for $84.99, which is great as I have 4GB of DDR3-1333 RAM that I ordered a while ago that I can use. I would replace that with the M3A78-EM in my second desktop (it's used for gaming for friends when they come over, as well as a LAN PC that I take to my buddy's). I can also get a Sapphire 6790 for $139, which would replace my 4670. I could use my 4670 in my home server to offload some work onto the GPU (am I correct about this?). I have a Athlon II x2 250 just sitting in a box doing nothing right now. Would that be enough for the home server for 1080p content, or am I better off picking up something like a Phenom II x4 840 for $100 instead?

Thanks in advance!