Win 7 and/or manufacturer support can be a problem. Using a x64 version of Win 7 always limits the number of drivers available for hardware. But you might check the Canon site to see if they supply a driver for your Win 7 version. If not, there may be a Win 7 driver, but it seems if there was, it is not working very well.
You might be able to use a Win XP driver or Vista, if you run it as such and a driver for your version (x64 or x32) is available it might work.
Another option might be to use Vuescan software, if it has support for your device. It does seem to require a basic driver from the manufacturer to function.