Something must be in the air - we moved servers too, physical to virtual
I just rsync'ed everything over from the old server to the new, stopped, did a final rsync and then moved the name and IP to a secondary interface on the new box.
Then I cloned it and set up an rsync to the clone - if the primary dies we can just move the IP to the new box and we should be good to go.
The "reconfigure client" thing bit me a couple times - xymon hardcodes the host IP into the binaries. I cloned a dev server and it fired up and started happily sending data to the primary before I rebuilt xymon.
Oh and since our xymon server is on the vmware cluster - I also have another xymon server sitting on a physical box, doing nothing but watching bbd on the primary. It's job is to alert us if the primary xymon server goes down.
I did manage to take down the primary a few weeks ago, by loading it up with some server-side scripts that were failing to return. I'm trying to get away from running server-side scripts on the primary now.