A couple of links partly answer my questions: Terje J. Hanssen wrote:
Well, it looks like Linux XEN at least currently cannot or is not allowed to host Windows. http://www.cl.cam.ac.uk/Research/SRG/netos/xen/index.html In addition to Linux, members of Xen's user community have contributed or are working on ports to other operating systems such as NetBSD (Christian Limpach), FreeBSD (Kip Macy) and Plan 9 (Ron Minnich). A port of Windows XP was developed for an earlier version of Xen, but is not available for release due to licence restrictions.
Besides the Novell and Xen plan, AMD and Xen also told that they will port Xen to AMD64 technology. Does somebody know if the dual core Opteron processors AMD just launched will play a role here?
http://wiki.xensource.com/xenwiki/XenFaq#head-fcb85a149da66907086cc8ba4f0793... 1.4. Does Xen support Microsoft Windows? Unfortunately we do not currently support Windows; the paravirtualized approach we use to get such high performance has not been usable directly for Windows to date. However recently announced hardware support from Intel and AMD will allow us to transparently support Windows XP & 2003 Server in the near future. We are working on this and intend to have support available by the time the new processors are available. Terje J. Hanssen