I've got a small project on at the moment along these lines. I was given a PC the other day at work, it's only a Packard Bell, it's got 512 meg of DDR2 ram and a Celeron 3.33 GHz CPU the only thing it doesn't have is a hard drive.
Not quite sure what I'm going to do with it, but I'm ever so tempted to make it into a file server.