I've got a dual xeon, 2GB, 75GB hd server that I'd like to turn into my dedicated virtual environment. Currently I'm using VirtualBox locally to run a mock cluster for Cassandra and Nginx/Haproxy, but it's starting to overload my system. I'd like to run Arch for this box and have a minimal desktop environment with either KVM or Xen managing all the VM's. Anyone know of a good tutorial or should I just do the base arch install and then find a good tutorial for setting up Xen/KVM and managing the machines? Also, which would be better for this type of environment. I've read that kvm is the way to go because it's much easier to setup and manage but I do not mind a more difficult setup if I can make better use of the hardware with Xen.
An opinion on Xen vs. KVM that I agree with.
The performance is comparable with arguments on both sides at the moment. Time will tell which solution gets the most love (and improves most) in the long-run. My guess is KVM.
Red Hat is investing quite a lot of time, energy, money, and risk to move away from Xen to KVM. Would they do that for no reason?
This is not a complete answer to your question, but with regard to performance there is a KVM vs Xen question on Server Fault that might be helpful.