Did you installed the right driver? I found for you Canon Canoscan Lide-100 driver v.14.0.1. But have no idea if it is also for the Vista x64, or just for 32bit operating system. Hope it helps.
Thanks, I did follow the link and downloaded the driver, which it said was compatible with 64-bit, but I am still getting the message: Canon driver supported by this software is not installed." I'm a bit stumped as to what to do?