I have heard of one other option:
Halsign TurboGate Tools http://www.halsign.com/
I haven't tried them personally, but I have seen them announced on the Xen mailing lists.
Thanks Todd,
I did try loading the Halsign RPMs, but my mistake I forgot about the LGPL PV drivers I had loaded some time back and it crashed the test VM - it wouldn't start. In the end decided to play safe and just went with Windows on bare hardware (non virtualized) as this machine is mostly file serving and is remote.
Have a number of Xen Linux on Linux systems which are very successful.
Regards Stephen