Yes, you can install a second hard drive in many computers. The installation depends on your setup. The best case scenario is you get a hard drive that your bios supports, 80gb would be a safe bet being that your pc is a little old. You just open the case, slide it in a free 3.5 inch bay, put in 4 screws. Set the jumper to master or slave depending on your setup and then put an IDE and power cable to it and you are done with the hardware part. Just boot to windows and make a partition and then format