The activation process keeps track of number of times you have used a product key. If this is your 4th installation you may get message saying you can't use this product key. Make sure you uninstall from one of the other machines. If it won't allow you to
activate, you will have to do a phone activation and tell the service rep that you have uninstalled from one of the previous machines.
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http://office.microsoft.com/en-us/outlook-help/learn-where-menu-and-toolbar-commands-are-in-office-2010-HA101794130.aspx - Silverlight applets Mapping 2003 menu to 2010 ribbon for all Office apps.
http://office.microsoft.com/en-us/training/HA102295841033.aspx -Flash Applets mapping Office 2003 menus to 2007 ribbon.