What button is this assigned to on a keyboard with Mac drivers but not the button?
Try F12 that might work, tho I'm not sure if the Apple Keyboard drivers will actually do anything with a non apple keyboard.
Download "input remapper" link: http://www.olofsson.info/index.html?inputremapper.html
It's a nice, free windows keyboard driver for Mac keyboards.
I've used it to configure a couple other Mac-specific keys for use under XP as well.