OK, did you share the printer? What does "can not share that printer"
mean? What happens when you try? Remember that we can't see your
computers and don't know what you've done. When you say "file sharing is
working", do you mean you are able to share files between all the
computers on your network?
Take a look at this link to review file/printer sharing in Vista again:
Elephant Boy Computers
MS-MVP Windows - Shell/User