What is a media PC? Like you bought a really cheap PC just for storage and watching media or something?
I have 8 PC setup with 2 media PCs at my home. The media PC streams videos, music and family photos to a projector on my network. I also have crossover cables but I have not used that in quite some time.
You set up a LAN and use one of the machines for file dumps. It saves a ton of money so that you can use it for multiple purposes...like arcade gaming, private servers for hosting games, sorting and organizing family photos from your couch...whatever.
You can build for one less than $100 as all it really does is back up your files and such so you don't need a serious video card (if any). The major thing would be HDs, really.
In fact, a lot of people give away PCs like this all the time on craigslist. I picked up 12 PCs alone in December for the children's center that I volunteer at. 9 of them were working as is and the rest needed a little touch up and nothing more.