currently I am using Ubuntu 12.04LTS running samba as a fileserver for Windows and Mac machines. The performance is great and the server has lots of spare capacity. So I want to throw a few vm's on it (to run some simple tasks in a windows vm). I looked into a few options but I like xenserver with xencenter to remote manage it (the server is headless).
Citrix has announced this week that XenServer 6.2 is now fully open-source software. Citrix has made XenServer 6.2 available to all users as a free open-source virtualization platform, beyond just the Xen hypervisor that has been apart of the Linux kernel and one of the leading Linux virtualization systems aside from Linux KVM.