Multiple AD Users

[mikesmith20088002]

I have a new client with an existing Windows 2000 domain (less than 100 workstations) plus Exchange and ISA servers. Normally I have only worked in situations that I have build from scratch and never encountered this problem before...I have multiple instances of Active Directory Users running on multiple servers and while the domain is the same, the users don't seem to exist on each instance of AD users on each server (I know users entered on one of the domain controllers don't have internet access unless than are reentered on the AD users on the ISA box. I know that this setup is far from correct and I eventually plan to upgrade to 2008 and have just one AD with just one backup server to autheticate users.
But as I limp along with them; can anyone offer any advice on how to figure out;
1. what the primary AD server is for a domain?
2. how can I check on the client-side (all XP) to see what workstation a client is authenticatting to?
3. Is there a good, free tool for mapping AD? So I can make sense of this small yet messy domain?

 

[TechyMcSe2k]

1) Right click the domain in AD users and computers and choose Operations Master Then Click on PDC
2) net view %logonserver%

 

[TechyMcSe2k]

3)

http://technet.microsoft.com/en-us/library/cc757747.aspx