We love using the old computer as a media center. It has been awesome. The most fun thing we have done with it lately is to run the webcam so we can talk to our friends in South Dakota. But beyond that we also set the Picture in Picture on the computer to run the webcam on the bottom right side of the screen and we played Guitar Hero 3 with our friends through the wi-fi connection on the Wii.
The one thing we need to work on is the moments when we got some major feedback while playing, other than that it worked like a charm. Also I love that we can load up all our CDs and record our favorite shows without having to think about it. So much fun.