WMI can be used to determine if you have logged onto a workstation, member server, domain controller, etc. So if its not a workstation you could just quit before mapping drives.
Below is some code taken from a Hey, Scripting Guy! article to give you the general idea. The full article is here -> http://www.microsoft.com/technet/scriptcenter/resources/qanda/jan06/hey0117.mspx
strComputer = "."
Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\cimv2")
Set colComputers = objWMIService.ExecQuery _
("Select * from Win32_ComputerSystem")
For Each objComputer in colComputers
If objComputer.DomainRole < 2 Then
Wscript.Echo "This is a workstation."
Else
Wscript.Echo "This is a server."
End If
Next