Media Portal Rocks!
I've been looking for some good software for my Media PC that runs under Windows. Linux appears to be ahead of the game with open source packages such as MythTV. I finally found Media Portal which rivals the Linux offerings and blows away anything else I've seen on Windows (except maybe Microsoft's Media Center, but I dont' want to buy a new PC for this). And best of all it is free and written in C#.
Take a look at these awesome screen shots! More here.