In order for us to help you, we would need information on your system, mainly the motherboard information.
It could be that your bios cannot handle a hard drive that size.
You could use overlay software but i dont reccommend it as it always causes problems down the road.
The other, best option, if the bios wont accept this hard drive properly would be to use an ultra pci controller. This controller fits in a pci slot and allows you to install larger hard drives as it has its own bios in it that can see the larger hard drive.
Still, we would need your motherboard info to see if your current bios can handle that hard drive, but if not then the pci ultra controller card would be the way to go, and they are not expensive.
Good advice + great people = tek-tips