NT Group Membership in ASP

I am attempting to develop a web site that will present two different initial pages based on whether or not the user is a member of a NT group when they access the page. The outline is basically (all pseudocode, not necessarily true ASP):

Main Page:

NTUserName = Request.ServerVariables("AUTH_USER")

If MemberOf(NTUserName, "Privledged NT User Group") then
Response.Redirect("privledged.asp")
Else
Response.Redirect("standard.asp")
End If

Is this something I can do with intrinsic commands in ASP (using either VBScript or JavaScript), or is this something that I will have to use a third-party control to access the NT group memberships?

Thanks in advance!!!

Dan