I had a similar plan (can't afford it) that would run Windows Server 2008 w/Hyper-V. Vista Premium/Ultimate would run as a guest OS.
My planned hardware centered around an Intel Core2Quad Q8200, a Supermicro motherboard (only Intel board I could find that supported Server 2008 out of the box) and 8 Gig of RAM. Add in with that a mainstream graphics card (ATI Radeon 4650), a discrete sound card for DVD/Video playback and a TV Tuner and you should be good to go.
At least that WAS the plan.
-Wolf sends