Which home theater PC should I order?

Hey, so my boss has asked me to include a home theater PC along with some other workstation ordering we’re doing. I had a MythTV box for a while, but he’s looking to just have something like a windows mediacenter PC. I think he’s looking for a set top box/jukebox/basic internet from the couch, but not DVR—he’ll do tivo for that.

I have no idea what to spec out… the criteria will likely be:
1. Something off the shelf from dell
2. Additional software is okay
3. Runs some sort of microsoft software.

I know people have done this with mac mini’s, is that a better/friendlier solution? Frontrow works well as a 10’ interface, all his stuff is already in itunes. IR keyboard/mouse for surfing?