old PC to file server

well, i dont wanna spend the cash for an external harddrive. i did like 2 min of research for this. could i take my old PC, get a bigger drive, and run that as my server? i only want a tower, no monitor, no keyboard, no mouse. i want to be able to hide it in my room, and still allow everyone else to use it. I have a wireless router too. does that make any sense?? thanks.

This may be overkill: http://www.openfiler.com/about/
This may be perfect for you: http://www.serverelements.com/

have fun!