External Keyboard Not Working, WHY?

Please help.

I have a new external keyboard (no particular make or model) with a standard USB connection.

I plugged it into my macbook pro and it worked straight away with no problems.

When I tried to plug it into my PC Laptop (Windows 7) it didn't work. I've tried updating the laptop drivers & Microsoft updates but still nothing. It won't even register it in device manager. I've tried setting the USB KEY in the bios to boot priority but still nothing.

I know it's not broken and I know it's either my PC Laptop or Windows 7. Which one and how do I fix it? Any ideas?