Build a Linux Media Center PC
Media Center PCs have been around for almost a decade—even longer if you count earlier forays like Gateway's Destination PC lineup from the mid-1990s. It's not just about PCs, either. More recently, we've seen set-top box media extenders and media-focused game consoles like the Xbox 360 and PS3, as well as targeted peripherals like the Slingbox PRO-HD and the Hauppauge HD PVR. All have garnered their share of fans.
Unfortunately, many media center setups are inflexible. The Apple TV is probably the worst example; it's tough to do much with that box unless you're a slave to the iTunes Store. (Or unless you hack it.) But even Windows 7 and the Xbox 360 can be unnecessarily limiting when it comes to your media.