Problem initializing keyboard in XP Pro.

I brought my desktop up to a friend's cabin for use at night while I am here. His old one (which I'm on right now) is a Pentium III, so you can imagine why I'd rather use mine. Anyway, to get to the point, he has a ps/2 mouse and a usb keyboard. When I plug them into their respective ports on the side of my desktop and turn it on, the mouse initializes, but the keyboard fails to do so. As such, I cannot type in the password to get to the desktop. I'm not sure whether the keyboard drivers should install themselves even before getting to the desktop, but when I installed XP Pro, I had a hitch and driver.cab wouldn't install for one reason or another (yes, the disk is legitimate, nothing wrong with the RAM, I ran Windows Memory Diagnostic and Memtest86). Anyway, that hasn't caused me troubles up to this point (for all of my components, I used the driver CD that came with the motherboard), but perhaps it is the reason now.

So, I suppose what I'm asking is if there is any way to get past entering the password so I can get to the desktop and subsequently install keyboard drivers? Thanks in advance for the help!