I've got a 2nd computer that has been sitting in the corner of my room for the past few weeks doing nothing at all. I'm not too sure what to do with it at the moment.
AMD Athlon 3200+
Nvidia 6200(GT I think)
I was thinking of trying pfsense on it since it allows you to also file share but I have zero exp with xBSD Systems.
Play and learn OpenBSD or the ins and outs of RHEL/CentOS. I say go OBSD, but ..... thats just me ;D