Usign LDAP or ADSI
i know:
my server is server NT
name of domain=dip
name of group=my_group
name of user=my_user
With a input text box named "insert your userrname here"
and a post button "verify"
After pressign button, validate the user name if is present in the group, if YES goto "ok", if NO write an attention message...
Sorry for my enghlis....