You could use the build in InGroup() function to see if a user is a member of an AD group.

If you want to see membership of a GroupB when the user is a member of GroupA and GroupA is a member of GroupB the there is a UDF called ListeNestedGroups (not sure about the exact name) that can show you membership of a group and membership if nested groups.
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Mart

- Chuck Norris once sold ebay to ebay on ebay.