There are still two more tasks that you might have to finish off before you can run the Migration Wizard without issue. The first is to change the folder redirection group policy and the second is to create a new user with administrator ability.
If you have folder redirection enabled, it means that all your documents are stored on the server as well as the user's PC. This needs to be pointed to the new server before the migration is started by checking and changing group policy in your domain. If you are not sure if it is enabled, simply follow this process and if the policy does not exist, then you are fine.
Having logged on the SBS 2008 system, find the folder Administrative Tools on the Start menu and then click Group Policy Management from the menu.
This will open up the GPO (Group Policy Object) Management tool. Here, you will see a combination of all the policies that were defined on the SBS 2003 server, including folder...