During your ConfigMgr 2007 to ConfigMgr 2012 migration planning, you may think to migrate your CM2007 reports to CM2012. But, can you?
swipe says it succinctly:
You cannot migrate Configuration Manager 2007 reports to System Center 2012 Configuration Manager. Instead, use SQL Server Reporting Services Report Builder to export reports from Configuration Manager 2007, and then import them to System Center 2012 Configuration Manager.