I need to find multi-homed hosts (multiple active network interfaces) by
looking at the registry. What information should I look for in the Windows XP
pro  Registry?

Why not use WMI to query the remote machine for multiple network interfaces?
There are plenty of sample scripts in the Tecnet ScriptCenter that you can
combine to locate network interfaces on a remote machine.

Or, you can look in HKLM\System\CurrentControlSet\Services\TCPIP\Adapaters
and HKLM\System\CurrentControlSet\Services\TCPIP\Interfaces.  You will notice
a bunch of GUIDs (depending on how many network adapters and network SHIMS
exist.)

I would still say that you are better off doing a WMI query.

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