You can boot with your PS/2 keyboard and plug your USB keyboard later to see if it is recognized. There is nothing wrong with having both keyboards. But DON’T unplug you PS/2 keyboard while your computer is on!
Also make sure that other USB devices (on the same port) work.
Does that keyboard work with oher systems? Is your keyboard a new model (which might possibly not be supported by 11.1 hal daemon - responsible for detecting hardware). If so try to boot openSUSE 11.2 livecd!
there is an adapter plug converter to connect usb keyboard to ps/2 socket.
else while installing keyboard selection choice must be changed
check if there is a configuration of keyboard change available in yast.
it is the X server to find this usb keyboard.
Don’t use that! It will be seen as ‘generic keyboard’ by the hal daemon. It might work though if that’s what you want, but extra keys if any won’t be available. You should avoid USB to PS/2 adapters noawdays.