IMPORTANT!!!! Remember to never hot-patch the firewire(at either end) as that will often fry the FW chip in the 002/003(and sometimes take out the computer FW port too)
First off, you posted this in the Mac section, so most won't be much help. Having said that. the driver is available(via the Learn & Support link at the top of this and every DUC page). You probably want driver version 9.0.2.65***(download to a USB stick and drop on the desktop of the XP machine)
***BUT*** before installing that, does your friend have the LE7.4 installer disk(or download) and authorization code? With LE 8 and older, the driver gets installed along with the LE software. Here's what I would try:
#1-With everything OFF, connect the 003. Power the 003 ON, then boot the computer with the LE7.4 disk in the optical drive. When the system reaches the desktop, you SHOULD see the "Found New Hardware" message. With the disk in the drive, it SHOULD find the driver.
#2-if above failed, power the 003 OFF and uninstall the old driver. Then install the download and reboot(power the 003 ON during the reboot).
#2-if above did not work(and you have the authorization code for LE7.4), uninstall Pro Tools(003 connected, but powered OFF). Reboot>run the installer(disk or download). At some point, the installer will tell you to "Connect Hardware"(or something like that). Power the 003 ON, wait maybe 8 seconds, then click Okay to continue the install. Once that finishes, reboot and open Pro Tools(you will need his authorization code that starts with "DIGI....." for the first run).
Last 2 cents; its not a one-way trip IF(the big IF) you have a backup plan. My preferred plan would be to clone the system drive to another similar drive(normally I would go to an SSD, but I don't know if the old machine can use SSD, or SATA at all
). Second choice would be to save a drive image BEFORE making any changes.