WinXP and Active Directory Domains

I have setup 5 workstations that are all running WinXP and are totally updated with all patches. I have a Win2K Domain running Active Directory. I have been successful in inviting each of the workstations into the domain without problems, the problem occurs when we are trying to logon, it takes an excessive amount of time to logon to the domain, somewhere in the range of 5 – 10 minutes. I have checked my settings to see if it were a DNS issue, WINS, or hardware, but I have pretty much eliminated these areas. All 5 workstations are experiencing the problem. Any suggestions to review in my network that may cause this problem? I am not sure where to look next for resolving this problem.