I've been trying this for a couple of days now, migrating my site from the old yahoo host to the new media temple grid server.
I've done as (mt) asks, in as much as I made a back up of my DB and exported it from phpmyadmin. I then imported the database I used their (media tample's) one click install of wordpress. swapped my DNS from yahoo to (mt) and waited 24 hours. Now my Wp site moves very sluggishly, and I think it still pulls up from the yahoo host and not (mt) since on my (mt) server I dont have any plug-ins installed yet they can be seen on my site.
I've tried the (mt) support area and am generally told that it's not a (mt) issue since WP is a third party program.
What I'd absolutely appreciate, is some serious help... I have to step away from the computer for a while before I throw the monitor at a wall. My level of experience with any of this is slightly above none to minimal.