Hey,

So I tried installing fedora 13 on old pc (5+ years), the live cd boots ok. but when I click install to disk, the "starting Install to disc" tab comes up and then goes away, then nothing.

This comp definitely has a large enough hard drive. (are there ram requirements that could cause such a thing?). It currently has windows xp (and probably loads of viruses).

any help is appreciated.

Cheers,
Skynet

RAM, CPU speed and Front Side Bus all come into play. Suspect a problem with RAM. Choose between either Slackware-based or Debian-based distros. Kwort, Zenwalk, Salix for the former; antiX, peppermint, mint-9-lxde for the latter. These are in increasing order of how much RAM they "like." With Mint-9-lxde "liking" 768MB in my experience and the first one listed need as little as 256MB to run decently. Stay away from KDE and Gnome desktops, too.
My opinion based on experience with PIII and P4 machines - take it or leave it.
Best wishes!

Yeah it is a PIII. the ram is only at 320 MB right now.

would adding ram allow me to install fedora or ubuntu?

Maybe. More ram helps on bigger distros. A more lightweight distro might have a better chance.

Hard to tell. Older computers don't like burned cd. You'd have to check it booted on the specific machine.