Found on the european mustek site. consists of two files after unzipping. first run the fixwinxp.exe then run the run.exe. This will then install the scanner drivers, after reboot, it seemed to go through the normal windows process of detecting hardware and then installing again for whatever reason but it worked.
incase you can't unzip - here's the URLs
European URL for the winxp fix
European URL for the win2000 driver they say you need