I currently run a HP m8120n. (Refurbished from Newegg for $600 delivered. I couldn’t build a new box for anywhere near that.) It has an Intel quadcore Q6600 at 2.4ghz, 3gb RAM, 2x320gb HD’s, Hauppauge digital tuner card, and I threw in a Radeon 3650 video card because I didn’t want to bother with a new PSU. I have an HP Media Vault for media storage/back-up and it has 800gb of storage. I have several Seagate external USB drives ranging from 250-500gb. I’m trying to get started ripping hundreds of CD’s. I use a 24″ BenQ Super PVA LCD monitor because I hate the color shift and viewing angles on most consumer panels. I run Vista because that’s what it came with and I haven’t had a problem with it. I actually like it.
I use the media center a lot now. I still have a 32″ CRT for my livingroom home theatre. I run a composite out from the PC to it and use the HP remote to stream content. Works fine for standard def and video podcasts. Hope to upgrade to a HDTV soon.