I'm currently using an Athlon 64 latptop with an external 2tb USB HD and an Audigy notebook sound card as a media center and shared drive (and torrent, and server, and backup ...). I use either MediaPortal or XBMC.
I want to make a new one from scratch. I plan it to be an i3-2100 or 2105 (I've read the 35w version saves only an average of 2-3 watts IRL) with an H67 or Z68 chipset card. I will choose one with a legacy PCI because I have a PCI-to-PCMCIA adapter for my Audigy Notebook. I will internalize the USB drive, but perhaps use a 150 gb 2.5" laptop drive as the main one for energy and noise issues. It will have 4gb of ram.
I also have an USB AverMedia digital tv tuner, which I don't use but will on the new PC. And, of course, a gamepad Remote isn't missing: it's a generic one for windows. The speakers are a logitech x-540 set and the TV is a 40' Bravia.
I plan to use Win7 and MediaPortal / XBMC (as I'm doing now). The new thing is: I plan to set up a virtual PC with a home server solution (such as FreeNAS) with exclusive access to the 2tb hard drive. It will also be in charge of P2P and everything server-related (including serving for the Media Center it will be built into).
And that's the plan. I would like to know opinions and suggestions. At first I wanted to make an standalone NAS with an Atom solution, but it didn't get through the WAF (wife/wallet acceptancy factor).
Thank you all for your help.