I am currently looking into whether moving away from VMWare server will be a good thing. It has been quite some time since VMWare updated their server product and it is becoming more and more difficult to manage it without implementing a lot of hacks and workarounds. Currently, I am simply unable to initiate a vmware-remote-console session using Firefox 3.6 and there is no solution in sight.
I initially looked at KVM, which is the "official" ubuntu virtualisation platform but that plan fell by the wayside when I realised that KVM requires hardware VT extensions in the CPU and if they are not found will fall back to full-on cpu emulation using qemu. The Atom processor on my server is already underpowered without trying to run full x86 emulation in software. Therefore, I'm back to trying out VirtualBox.
The problem with VirtualBox is that it does not have a high level management system for the machines on the host. It is all text console based which I normally don't mind, but I do find that it is very convenient to fire up a web browser to take a quick look at which machines are currently running and the details for each one.
You can't do this with VirtualBox.
Then there is the uncertainty surrounding Oracle swallowing up Sun. There is no guarantee that Oracle will keep developing and supporting VirtualBox or indeed whether it will remain free.
Already the Open Source Edition lacks certain features such as headless operation and decent usb support which means we need to use the "full" edition which must be downloaded from the Oracle website. Currently, VirtualBox is free, as in beer but unfortunately Oracle have a long history of charging exorbitantly for everything they possibly can get away with. Most recently this was demonstrated by their insane decison to start charging $90USD for an MS Office ODF plugin that was previously available for free while at Sun.
There is nothing to say that they won't do the same thing to VirtualBox.
However, despite these concerns I am still willing to push on. The only alternative is to replace my hardware with VT capable gear which means spending money and vastly increased power usage. Avoiding these things is the whole reason I went with the Atom board in the first place.
At least until I can find a motherboard that ships with one of the VTx enabled Atoms (Silverthorne Z520, Z520PT, Z530, Z530P, Z540 and Z550) on it anyway.