Linux as backup (failover) machine

Hello everyone!

I've been posed with a question, and I'm a little stumped... please bear with me.

Problem:
Make a Linux machine automatically kick in as a failover machine for http when the NT machine goes down.

Restrictions:
Need to be able to monitor the NT box without installing anything extra on the NT machine.
Linux machine needs to be able to kick in automatically when the NT box goes down, and give control back to the NT box when it comes back up.
No access to installing any type of router/proxy between the NT and Linux box and the rest of the net.

Please send your ideas either directly to myself, or to the list if this problem is of interest to others.

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Ken Bowley/SysAdmin            mailto:johann@vikingsystems.com
Viking Systems, Inc.              http://www.vikingsystems.com
-=-=-=-=-=[Sair Linux and GNU Certified Professional]=-=-=-=-=-