When Fred has Bobs credentials he can log into computer with the Bob account, impersonation is no different. You can't tell which person is actually logging in with a Bob account without doing a fingerprint or eye scan.

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See this thread about how to use forum markup codes for code blocks etc (present the problem/post properly )
Some useful links: Learning videoes, WMI Code Creator, MSDN, The Code Project, WindowsClient.net, ASP.net, W3 Schools, Regular-Expressions.info, GDI+ FAQ

DR. WEIR: Download it to a non-networked, firewalled computer.
TECHNICIAN: Yes, ma'am.