Set objADSysInfo = CreateObject("ADSystemInfo")
strGroupCN="CN=Domain Admins"
If IsMember(objADSysInfo.UserName,strGroupCN) Then
    WScript.Echo objADSysInfo.UserName & " IS a member of " &_
    strGroupCN
Else
    WScript.Echo objADSysInfo.UserName & " is NOT a member of " &_
    strGroupCN
End If

Function IsMember(strUserPath,strGroupCN)
set objUser=Getobject("LDAP://" & strUserPath)
strGroups=UCASE(Join(objUser.Memberof))
'case-sensitive string comparison
If InStr(strGroups,UCASE(strGroupCN)) Then
    IsMember=True
Else
    IsMember=False
End If
End Function