All the solutions to get the Mustek 1200cp scanner working using the W2k drivers in XP failed for me. So I installed it under W2k on a different PC. These are the files which the install put in the WINDOWS\TWAIN_32\CIS600X subdirectory in the W2k install. When I copied these to the XP's WINDOWS\TWAIN_32\CIS600X directory (after a failed install) it supplied the missing files and my scanner came to life.
And if your system lists unknown devices from previous failed installs which you can't delete, you can do this in the registry (search for 'mustek'in regedit). If it will not let you delete these then go to Edit/Permissions in regedit and give yourself full rights first.
Already tried it? Give your review.