i bought a maxtor 80 gb, i just want to use it as secondary drive.. but i don't know how to install it on my MOBO. im running XP pro. tnx

I am assuming you are using a EIDE drive since you did not state other wise. On the side of your drive should be a diagram of how to set the jumpers on the end of the drive near your data cable plug.
Configure your drive to SLAVE. Locate your current primary hard drive. There will be a flat cable coming from the motherboard to that drive with an unused plug on it. On that cable there will be a red soild or dotted stripe on one edge. When you plug the drive in the red stripe should be nearest the 4 pin power plug next to the EIDE data plug. Insert the cable plug using care not to bend the pins. Make sure your drive is firmly attach in a drive bay and the cables are plugged in, both power and data.
That should do it.