Macintosh Keyboard on a Dell Laptop

I have been issued a new Dell Latitude D620 laptop at work. The keyboard from my old machine doesn't work with it because it's not USB so I brought in one of my Mac USB keyboards from home. However, the Dell doesn't recognize the keypad, and since there is no Num Lock key, I have no way to mechanically turn it on. I checked the Keyboard control panel but there is no function to map the keypad. Does anyone know how to do this? Is there a driver that I need to download or third party software?

Thanks in advance,

Chris