Windows Authentication

[Erik van Kruiselbergen]

I created a database driven web application in asp.net
(c#). Now I need to create queries on the database, based
on the groupmembership of the visiting user.
I can get the login ID of this user by using

String strUID = Request.ServerVariable["LOGON_USER"];

now in VBScript I would do something like this

FUNCTION ISMEMBER(sGroup)
Dim UserObj,GroupObj
if IsEmpty(GroupDict) then
Set GroupDict = CreateObject("Scripting.Dictionary")
GroupDict.CompareMode = vbTextCompare
Set UserObj = GetObject("WinNT://" & UserDomain & "/"
& UserLogonID)
for each GroupObj in UserObj.Groups
GroupDict.Add GroupObj.Name, "-"
next
set Userobj = Nothing
end if
IsMember = CBool(GroupDict.exists(sGroup))
end function

A call to the function would look like this.....

if IsMember("Internet_Users") then
<your code here>
end if

Is there a way to do this in ASp.Net using C#??
please help I need an answer urgently.

thanks in advance
Erik