Vista - credentials question: seek syntax for domain administratorOpenDSObject arguments

I have this clip of code that checks if you are a local Administator
on a computer:

' Bind to local Administrators group on computer.
Set objNS = GetObject("WinNT:")
Set objLocalGroup = objNS.OpenDSObject("WinNT://" & strComputer _
& "/Administrators,group", strUser, strPassword, _
ADS_SECURE_AUTHENTICATION Or ADS_USE_ENCRYPTION)

What is the syntax to OpenDSObject to connect to the global domain
controller?

I'm writing a script that adds users to AD groups that are used in
system wide application that uses NTLM authentication.

I have an account that has permission to manage the groups - but users
can't use that account to log into a computer.

Thanks.

I think the answer to this is:

Set oUser = dso.OpenDSObject(strUserDN, strUsername, strPassword, 1)