Yes, Xen is quite nice... unfortunately a lot of my hardware doesn't play too well with it (no VT bit). So I use it when I can.
Also an FYI for those playing with VMWare Server 2.0 and all this HA/DRDB stuff. The workaround for moving the VM between machines is a little different. You're no longer prompted in the GUI for the 'always keep' or 'always create' options. So moving the VM between them can be a problem.
The fix is to add the following line to the .vmx file for each of your virtual machines. It will keep the UUID (mac address ,etc) the same as you shutdown/suspend and move between hardware.
uuid.action = "keep"
I'm still working on some details for doing all this automagically on vmware 2.0. Will post when done. Right now my play environment is a pair of Dell 2850's using the Proxmox bare metal install. Then I installed VMware Server on top of it. So I can use OpenVZ/PVE and VMWare at the same time on the same host. Pretty spiffy.