Anyone have any luck upgrading ubuntu 8.04 to 10.04 and want to post a how to?

I am on a Link-4 using XEN.

I have upgraded many Ubuntu servers but never on a vps XEN. I've done the standard ubuntu upgrade (sudo apt-get install update-manager-core sudo do-release-upgrade) on dedicated servers before but never on a vps.

Any easy way to back up the server before attempting to do the upgrade (I run some servers in citrix XEN server and live by the snap shot feature) as I would feel much better with a backup incase something goes wrong.