You might want to look at VMWare or even the MS Virtual Server products to provide a virtualised environment (I'm a big fan of both).
There are several methods to copy a physical machine to a virtual machine, such as :
http://www.vmware.com/products/converter/
However, this is for offline use and allows a switch over. If you're looking for resilience, then migrating to a server farm with SQL clustering is the way to go (and way to crank up the expense too). You can then go even further and have standby server farms, hot or cold but it really all depends on the business requirements, how fast you want to be back online (or if offline at all) and what level of budget you have - I've seen resilient MOSS farms costing well in excess of £100k and some simple resilient server farms costing <£10k (of course the cheaper ones have limitations like all in the same place, dependant on the same power supplies, etc).
Paul Leigh
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Designer of PhoPho & PhoTab, photograph frames that double up as tablet and smartphone stands.
www.jackdawdesigns.com