One person for 400 users

I work at a shriners hospital with more then 200 computers and at least 400 users! I would like to hear from other support people on how they handle large groups of users, and who gets help first. We have every thing from win95 to 2000pro on the desk tops and NT4.0 to 2000 server on the servers. So I am vary busy and always on MS site to learn or find out why something dont work. So any help or tips would be great.