I do wonder if it will work for ESXi tho, it is after all a free Virtualisation product from ESX, if you want Enterprise capable Virtualisation you really need to pay for it.
Add to the fact that you can't manage the ESXi box from a centralised management point (ala V-Center) without buying the licence for that.
If you want HA you are going to have to pay for it somehow, whether it's done via Doubletake or VMware themselves.
I also mentioned in the VMware forum that you could always use VCB to do backups via BE (which is your current backup medium) but again that's going to cost unless you want to do it all via scripts (using the VI plugin for BE will be a lot easier).
VI should never be seen as the cheap alternative to physical hardware because it's not, you have to ensure you have plenty of ram\cpu horsepower\ storage etc, more than a normal server would have (our ESX nodes all have 64gb of ram, that's approx £30,000 of ram alone).
Oh and fyi both ESX 3.5 and vSphere have V-Motion, infact ESXi has it... once you purchase the license for it.
You don't virtualise because you want cheap servers, you virtualise to cut down on your server room footprint and power and cooling costs.
The real world is not about exam scores, it's about ability.