If you have a 64 bit operating system and an older Canon scanner (mine is a Canon 8400F so not that old) you are likely to have problems getting full functionality with 64 bit W7, even with the Canon 64 bit driver and software. In particular, transparency adaptors do not work.
For some years I've used VueScan software for scanning, probably the best for any scanner so when I went to W7-64 recently found I'd lost functionality on my scanner and VueScan did not work with it all
However, a few day's ago, VueScan v9 was launched with a 64 bit version. This has solved all the problems and my scanner has a new lease of life, transparency adaptor included
It can solve problems with other older scanners too where there are no 64-bit drivers; VueScan provides them for you
Terry