Advice for media center PC

I love my current AppleTV gen 2, but I've decided to move to something with more horsepower for 2 reasons -- (1) I want to add a video cam so that we can video conference with family sitting on the living room couch (my brother in law has a set up that works really great for out-of-state grandparents to watch all our little kids running around) and (2) I want DVR functionality for my OTA network channels. I also want to replace the current functionality of my AppleTV -- mainly, access to iTunes library and Netflix.

So, I'm thinking a Mac Mini with Plex (wish there was a Skype/Facetime plugin) and DVR software. I did a quick search for a less-expensive, comparable Windows-based alternative. With a Windows-based box, I think I could get by with Windows Media Center for both DVR functionality and to access my movie, tv show and music files. But I would end up having to figure out how to run WMC and iTunes (to serve up content for my other AppleTVs in the house) content databases concurrently.

So I recognize there are a lot of kinks to work out, but my main question is whether anybody has a suggestion for a windows-based Mac Mini alternative. I like the small form factor, but box size isn't a big issue. The Mini just appears to have pretty good specs for a media center computer.

Thanks for the thought. It would be a fun project, but even though I'm pretty techie I think there would be a significant learning curve for me to build my own PC - and I'm afraid I don't have the time or patience right now.