Vista - UserName returns SLUser

I'm using Desktop Authority to execute a script for a couple of
hundred users. Mostly Windows XP boxes...

The code that gets executed is returning a UserName of 'SLUser'
instead of the person's actual login ID.

I've tried a couple different approaches, such as this:

Dim strUserName
Set WSHNetwork = CreateObject("WScript.Network")
strUserName = WSHNetwork.UserName
msgbox "User Name is " & strUserName

Any suggestions on how I can capture the actual user's login ID?

Thanks!
Cole