External usb hard drives do not require a driver when used in Windows XP. If it doesn't work then you have one of the following problems:
1: USB Port problem
2: USB cable problem
3: Defective drive
1st thing I'd check is the usb ports in Device Manager to insure they are working properly.
All 3 of my usb drives are detected automatically within 4-5 seconds after plugging them in.