The driver for MSC mode is the generic USB driver in Windows. You could try uninstalling your USB ports, but make sure one of them is not your computer’s video camera, or you’ll have to find the driver for that afterward. After you uninstall, reboot and the computer will detect the ports.
The driver for MTP mode is in Windows Media Player 10 or 11 (not 9, the original version included with XP). So rolling back (if you have WMP 11) or upgrading (if you have WMP 9) should install that driver.
