I'd try to setup a Win domU for a while.
Try it with different configurations, different image files, again and 
again.
First, all seems to be fine. The setup starts, then there is the choice 
to press F6
to select SCSI drives (or the hint F5 for different setup methods),
the Win setup loads the drivers and in the moment it should show
the information to press Enter for start the main setup the screen get black
(sometimes there is a blue screen for a few seconds which says something
because hard disk problems or so)
A few minutes later the domU shutdown by itself.

Here the config file:
#==================================================
kernel = "/usr/pkg/lib/xen/boot/hvmloader"
builder='hvm'
memory = 512
name = "winxp-hvm"
vif = [ 'mac=00:16:3e:00:00:14, bridge=bridge0, type=ioemu' ]
device_model = "/usr/pkg/libexec/qemu-dm"

disk = [ 'file:/xenimg/windisk.img,ioemu:hda,w', 
'file:/data/cdimg/wxpsp1.img,ioemu:hdc:cdrom,r' ]
# disk = [ 'file:/xenimg/windisk.img,ioemu:sda,w', 
'file:/data/cdimg/wxpsp1.img,ioemu:hdc:cdrom,r' ]

boot='d'

ne2000 = 0
#==================================================

If i use the second disk line (sda instead of hda),
then there is the information i did wait for.
So now i press enter to start the main installation. And now ... sorry, 
couldn't
found any hard disk.
What, Why? But ... i did create some images at different ways e.g.
dd if=/dev/zero of=/xenimg/winxp.img bs=1k seek=8096k count=1
(but not only this way) It seems that it don't like my images.

With NetBSD 3.1 as hvm domU all was fine. No problem.

I'd read somewhere that acpi should turned off at Win setup.
To do so, i have to press F5 instead of F6 at the SCSI option.
But ... there are no reaction if i press any F key, nor F5 and not at F6.
Not within a vncviewer and also not if i use a xterm window (no vnc).
I couldn't believe that this schould be the reason of my problem with
the hard disk which isn't found. But i am also interested in get this 
working.

here is one of my /var/log/xen/qemu-dm.xxx.log files:
domid: 10
qemu: the number of cpus is 1
shared page at pfn:1ffff, mfn: 5e070
buffered io page at pfn:1fffd, mfn: 5e072
Register xen platform.
Done register platform.
False I/O request ... in-service already: 0, pvalid: 0, port: 0, data: 
0, count: 0, size: 0

Any suggestion? Any further information needed?

regards,
Rainer