How many servers?

I have 3 schools each with 200 students and each with approx 50 computers or workstations all running NT4. Each school is about 1/2 mile apart. I want to upgrade to a single Domain system running 2000 server. We have Frame Relay and routers in placein each school now. We need DHCP, Log in Services, File services,Print Services, Email services only…no web server. The server I initially priced and spec.was a single cpu 800 piii,512r,4-18g scsi hd raid 5, dual nics, redundant power, tape back up. With 2000, I shouldn’t need a BDC???? How many actual (hardware) servers do I actually need to purchase? I don’t know 2000 that well.
Thanks
Merv