ASGAUR

rsync works great on production enviroments, We had paravirtualized some servers with these method:

 rsync -ave ssh --exclude=/proc --exclude=/sys --exclude=/dev (if you are using udev) root@runingserver:/  /mnt/newserverimage/

after this:

 mkdir /mnt/newserverimages/proc

 mkdir /mnt/newserverimages/sys

 mkdir /mnt/newserverimages/dev

 review your fstab, and copy the kernel modules:

 cp -pr /lib/modules/2.6.16-xenU /mnt/newserverimages/lib/modules/

 more or less .... this is the way

 Also I have full virtualitzed some old GNU/Linux boxes with kernels 2.4,

I used GNU/Linux live CD on the old box and dd utility:

 dd if=/dev/hda | ssh root@192.168.1.1 "/bin/dd of=/dev/vg00/newvserver"

or

 dd if=/dev/hda | ssh root@10.10.52.118 "/bin/dd of= /dev/vmvg01/classicapp02"