Ben has an interesting post on how to boot Windows XP using KVM on Fedora Core 9. The interesting part is that Windows XP is installed on the host's hard disk. His instructions almost work verbatim, but there's one exception. Since I'm using KVM-73, the QEMU command is:
$ qemu-system-x86_64 -hda /dev/sda -net nic -net user -m 1024 \
-cdrom fixntldr.iso -boot d -std-vga
This will also give the guest system access to the network.