Is there some sort of guide somewhere showing the best way to migrate between 2 servers?

Here is my scenario -

I'm hosting around 300 small business clients (web/email/database) on a LAMP server with Plesk 7.5.4.

I use ns1.ev1servers and ns2.ev1servers for the name servers.

I've just ordered my new server (also at theplanet). It's basically a newer/faster version of the old server. It will be Plesk 8.2, with new php/mysql, etc.

I'm most likely going to be using the name server on my new server so I can setup automatic hosting signups (and dns record additions) using modernbill.

I think I'll be fine using Plesk Migration Manager, however I'm concerned that during domain propagation (ie. up to 24 hours) the emails and database queries may go through the old server, after the data has already been migrated to the new server.

How can I ensure that all data is redirected to the new server during migration/propagation?

I've seen Squires post relating to this at http://forums.theplanet.com/index.php?show...&hl=migrate

Is that the best method or is there something better?

ps. I'm most likely going to migrate in small batches over a few weeks so everything goes smoothly.