Slow logon to WIndows 2000 Domain

I have a Windows 2000 Domain running active directory, server is 2000 and all 10 workstations are 2000 Pro. My problem is the workstations take a very long time to logon. Once they are on everything is fast and works great. What can be the problem causing the delay? All machines are new and they are plugged into a switch. Everything looks correct to me but I must be missing something.