XP Comps slow to log onto 2000 Domain

I have a Windows 2000 Server with dhcp and have mixed workstations running Windows 98, 2000, and XP. My problem is the XP machines take a very long time logging onto the network. I put in the correct password and it takes about 5 minutes to apply the network settings and log on. The Windows 2000 machines are much quicker. What can be the problem?
George