Do you mean that you performed an in-place upgrade from Outlook 2003 to Outlook 2007? If so, then no migration was involved.
By "contacts view," do you mean the Contacts navigation pane? We need more details to know what you mean by "group."
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Sue Mosher, Outlook MVP
Author of Configuring Microsoft Outlook 2003
and Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers