Windows 2000 wireless keyboard & mouse driver

I purchased a Dell Dimension 4600 with the wireless keyboard and wireless optical mouse option.  The unit came with Windows XP, but it was flushed and loaded with Windows 2000 SP4.  The extra buttons on the keyboard (mail, my computer, calculator, volume, etc.) don't work, probably because the keyboard driver is missing.  Can anyone provide a link to the driver that will work with Windows 2000?