Installing ubuntu onto my 13 year old PC

Ubuntu 12.04 LTS should work fine, except for GUI 'features' which will be partially disabled. I would not try 12.10 (or 13.04), other than as an experiment (that may need to be undone).

You need to fix the keyboard, but using Tab should work for now. I assume you need this key to work in BIOS.

I would rather take the newest version of Xubuntu or Lubuntu than an old version of Ubuntu (definitely nothing that is out of support). Xubuntu should work just fine with a GUI and all the other stuff. I used it once with an older PC (1GB RAM, AMD 2600+) and it was pretty fast.

And if the Hardware is that old/bad there are still ditros like tinyCore