zac2003,
If you are moving from Plesk to Plesk, there are backup and restore tools that come with Plesk. You can find out more about them at the plesk website. They have been a standard part of the product for a while so they should be pretty solid.
If you are trying to move from Plesk to something else (like CPanel), I think you are out of luck in terms of automation. Each control panel uses its own proprietary data representations and tools. You'll probably need to move them by hand. This is what I had to go through moving from a reseller to RS. It's a pain, but quite doable.
BTW, why exactly are you moving? Are you unhappy with the server? with Plesk? Any specific issues you ran into?
I'm curious because I have the same setup as you (Duron + Plesk) and I'm wondering why you are dissatisfied with it, apart from the fact that RS now offers much better hardware for almost the same price (*sigh*).
-Danimal