Making a copy of production server

[xmario2013]

Hi All:
Does anybody have experience working with VMWare ESX or Microsoft Virutal Server 2005 ?

What we need to do is virutalize 3 of our phyiscal servers mirror them with the OS and application settings so that if in case any of the 3 production server goes down, we can bring up its virutal version and continue to serve users

and perhaps use for the other way around from virutal version to physical version when we upgrading the phyiscal server (with different hardware, is this possible to do?)

please share some idea if you have done this before

Thanks
XM