Have you tried Virtual Box and VMWare in addition to KVM and Xen? I am very happy with Virtual Box when I need to do something Windows-only. I only use Xen and KVM on servers. The run very well in headless boxes.

BTW, isn't Hyper-V somewhat related to Virtual-PC, the product Microsoft got when they acquired Connectix? If that's the case, it's one of the first desktop virtualization technologies. I used it extensively on my Macs in the early 2000's.