I have connected about 20 machines to 6.0.1-01, I am only a basic user, however for what it is worth this is my setup procedure;
1.Install XP Pro and do all updates ( I have not done one with SP2)
2.Go to system / computer name / change make sure that the computer is a member of a WORKGROUP, any name will do ( I normally use the same name as the domain) .
3.Make sure the computer has a name ( that you want to appear in Network places)
4.Reboot the machine
5.Run regedit and make changes HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\netlogon\parameters]
"RequireSignOrSeal"=dword:00000000
6.Reboot you machine
7.Go to system / computer name / change select domain and enter the name, click OK. When the login dialog box appears enter admin and the password for your sme.
After a while, you should see Welcome to Your Domain Name, click OK and it will ask you to reboot, do this and you should then be able to login. For your first login use admin and the password (same as you used to join the domain). If this work you should then be able to log off user admin and login with a normal user.
Hope this helps