Question : Migrating from External POP3 to Internal Exchange 2007

We are currently using POP3 to get e-mail from our web host server.
We have finished configuring exchange server 2007.
I need a lot of help migrating over with minimal down time. (Step by Step would be great).
I also have host DNS
1) Should I start changing the MX record?. This would take up from 18-48 hours to replicate right?
2) what are the common problems that we would run into during migration?

I would like as much as possible. and what is the best step i should take.
Thank you so much.

Answer : Migrating from External POP3 to Internal Exchange 2007

the big job will be importing users PSTS into exchange store...  mx change generally takes less than an hour - but yes can take up to 24/48

if you have alot of users you might want to tell all users that their psts will only be for archive purposes and new emails will be delivered in Mailboxes.

In terms of steps, if you are certain all email addresses are setup on user accounts etc then it really is just changing the MX from the hosting providing to your own in house. Also make sure you have some kind of antispam in place and antivirus. suggest EHS (Microsoft Exchange Hosted Services - you set them as your mx and they filter your mail).