http://linux.cloudibee.com/2008/11/vmware-to-xen-conversion
Here are the steps for converting Vmware windows/linux guest to Xen format. You need qemu-img tool (from the qemu-utils package) for the conversion.
You first have to ensure that your image has IDE drivers installed (see Microsoft kb314082)
Halt the vmware VM.
# qemu-img info FreeNAS-9.2.1.5-RELEASE-x64.vmdk image: FreeNAS-9.2.1.5-RELEASE-x64.vmdk file format: vmdk virtual size: 1.9G (2000027648 bytes) disk size: 846M
If the file format is “raw”, we do not need to convert the image file using qemu-img convert, just rename to file with the .img extension. If it is not “raw”, use “qemu-img” to convert the image to raw format.
# qemu-img convert FreeNAS-9.2.1.5-RELEASE-x64.vmdk -O raw /var/opt/localImg/FreeNAS-9.2.1.5-RELEASE-x64.img
Create the Xen config file in /etc/xen/guest22, with the renamed/converted image file as disk.
disk = [ 'file:/volumes/guest22/guest22.img,hda,w' ]
It should boot up fine.