Is it possible to install Xen on a computer (processor supports virtualization) alongside Ubuntu and Windows?

The computer currently triple boots Ubuntu and a couple of Windows versions. Now I want to add Xen into the mix. Would it work if I simply made a new partition for Xen, or does it need to take over the entire system? Alternatively, is there a way to bring my existing OS's inside of Xen (and run them together), so to say? In case I can't boot into the already installed OS's (together) under Xen, I'll settle for a multi-boot system (2 Windows + Ubuntu + Xen/XenServer) without destroying anything. Then I can do what I want after booting into Xen/XenServer. I'm ambivalent between Xen (with Ubuntu as dom0) and XenServer (with CentOS), as long as they do what I want (multi-boot).