Two things:
Yup , I have a cannon scanner, i think the b5000 and there is no windows 7 64bit driver for it, and also my canon a200 powershot camera wont be detected. The scanner driver always sucked in XP too, so no big loss.
In regards to Sharing files from Windows 7 to XP machines, default settings in Windows 7 dont allow permissions to all files on all hard drives in the system, I simply right clicked on the drive, went to sharing/persmissions, added "everyone" to the list and enable full control of the drive, now Windows 7 will share files to XP machines.
Some people say that opening up full control permission on a hard drive is risky, I say cow dung!, unlike some other people I am not trying to hide pron or keep such stuff away from kiddies, i dont have any. I have full security protection on all my files, nobody but me is requesting access to them, so I do it the way I mentioned above.