BEFORE you install this; make sure you have EVERYTHING ready to boot with Xen. If you don't, expect many lost weekends attempting to recover your system ... I really do NOT think the install script should Boot to Xen just because Xen was installed. Whatever goes down during the install, left my PC in an unusable state and even after I got things recovered; Xen again tryed to usurp the grub boot script. Poorly installed. BEWARE, there be dragons.
Powerful virtulisation solution with good documentation and easy to use administration tools, offering bare metal performance especially with VGA/PCI passthrough. Compared to KVM, Xen seems more mature, while KVM offers more flexibility regarding hardware support, at the cost of incomprehensive documentation. For those who need to run MS Windows guests with native performance, Xen is the answer (along with KVM).