if your motherboard supports fan control you should be able to set it in your BIOS setup utility. if it does support this feature many times the manufacturer will include software that will show you hardware temps and speeds in real time. you may be able to use that software to control your fan speeds in winxp, assuming your motherboard supports this feature. otherwise you'll need to use a hardware fan controller, these usually mount in a 3.5 inch bay. please list your motherboard make and model