Having installed my USB scanner and got it working I have tried to XSANE from the RH7.2 install. When I start up XSANE it says it cannot find the scanner. This is not a scanner problem as if I log on as root the scanner is found and works correctly.

I suppect that this is an access rights problem but I have following all the instructions in the documentation. Or have I?

If root can use it and a user can't, then yeah, it's probably a permission problem. As i don't have a scanner, I don't know what device name it will have. You may already know, it'll be /dev/something. You can just change the permissions of the device to a global setting like 0666 which will work for anyone, or you can create a special group that can only use it, add yourself to that group, change ownership of the device (chown) and then change permissions (chmod) of the device to something like 660, which only allows root and the group to use the dev.

I would suggest create a group named scanner, change the group of /dev/scanner (or whatever it is on your system) to scanner, and add regular users to the scanner group, usually acomplished through editing /etc/group file, you'll see
scanner:x:nn just add a colon and user names separated by commas.
scanner:x:nn:user1,user2

nn - group id number