You can have your group moved automatically, at no cost by Multiply, our online Groups partner. They will move the group’s content on your behalf and invite members to join your group.
To read more about Multiply's Groups service and how it works visit the Step-by-Step Migration Guide.
When you migrate your group to Multiply it still exists at MSN Groups, it is just copied to Multiply.  Unless the version of your group at MSN Groups is deleted by the manager you will still be able to see the MSN Group. After the manager migrates the group to Multiply members will receive an email inviting them to join the group at Multiply. If you join the group at Multiply and your MSN group has not been deleted by the manager you'll be able to see both your MSN Group and the new group at Multiply.

Managers please note, once you migrate your group, look for the members you want to be administrators. When they have joined the group in its new location you need to assign them the role of administrators by going into the Group Profile and settings.