for a k-12 school district with 2800 desktops. Will:

Two 2-cpu 4gb ram win2k3 servers be sufficient to support user login? I
know this is a little vague, but we are in the early planning stages. I
assume that lot's of student labs will login/logout at class start/end
times (ie concurrently)

Also --

How do we implement the round robin for a MidTier? Would we need a
hardware appliance or would windows DNS provide round-robin
functionality that would be sufficient?

Also --

How do we configure access rights to a non-zen Microsoft server for
access to application and/or imaging files?

Any help is appreciated!