I had an interesting challenge at work a few weeks ago. A customer wanted a new PC running Windows 7 but he needed to keep using his rather old A3 scanner, a Umax PowerLook 2100XL. Umax only provide Windows XP drivers and installing them on Windows 7 stops the system starting up.
Something about the combined installer for the software and drivers was preventing it from working.
The solution was to install the software on a Windows XP machine and then copy the files manually from the XP system to the Windows 7 one. I then pointed Windows 7 to the copied files when it requested drivers for the scanner. The application program was copied in the same way and I simply set up a shortcut on the start menu pointing to the program file.
Aside from the main program directory the drivers were spread out in various system directories. It took a while to find them all.
It took me a long time to sort all that out. There are a lot of posts on the internet written by people with the same or similar scanners who are unable to make them work on Vista or Windows 7. As far as I know we are the only people who have ever managed to make it work with Windows 7.