You can use User State Migration tool to migrate your Credential Manager data. To do this you are going to have to create a Custom.xml file. The following link gives you more information on how to create a custome XML file for USMT: http://technet.microsoft.com/en-us/library/cc749416(WS.10).aspx#Creating.
The link below gives you an example of a custome.xml file: http://social.technet.microsoft.com/Forums/en-US/w7itproinstall/thread/ab8d6d70-9d1b-419c-8149-37387d4eba6d
In our case, we are interested in the following line:
<component displayname="Microsoft-Windows-Credential-Manager-DL" migrate="no" ID="http://www.microsoft.com/migration/1.0/migxmlext/cmi/microsoft-windows-credential-manager-dl/microsoft-windows-credential-manager-dl/settings"/>
By setting the Migrate=”yes” option, your credential manager will migrate.