XBMC (click for download and info) ismy favorite media center software. It’s free and it’s better than it’s paid alternatives thanks to a slick, customizable interface that plays all sorts of media from the majority of networked and local destinations. It can pull content from the web, tell you the weather, double as a retro video game console, and much more. What’s really great is that it can run on a super cheap, underpowered nettop. That may also mean your old computer is entirely adequate for the job. Either way, you’ll be up and running a home theater system that’s ahead of its time before you know it.