Options for getting keyboard to work again?

Mac 10.6.2 (I haven't updated again since recovering from HD)

I've done all the troubleshooting that I can find online for this problem. My keyboard does not work. When I disconnect it, the Mac recognizes that a keyboard is not connected. When I connect it, none of the keys are responsive. I have recovered the OS using the DVD but no dice. I did NOT wipe the HD clean and reinstall. I've powercycled, etc etc. Still nothing. Trying to avoid buying a $50 keyboard if this is a drivers issue.

I enabled the guest account; keyboard still doesn't work. Trying to get my hands on a Mac-compatible board to see if the problem is the board itself.