At what point does the keyboard stop working?
It should work through bios. Does it work with lilo at the boot: prompt?
When it is not working, can you flip on and off the capslock light (if you have one)?
Is your potato up and running ok? Can you remote in to it and do stuff?
You should be able to type in characters while startup scripts are loading, even during kernel startup. At what point here can you not type characters on the screen?
Do you start xdm/gdm (graphics) on boot?
What if you start in single user mode? (at the boot: type 'linux 1').
Cory