AppLocker is available in all editions of Windows Server 2008 R2 and in Windows 7 Ultimate and Windows 7 Enterprise. Windows 7 Professional can be used to create AppLocker rules. However, AppLocker rules cannot be enforced on computers running Windows 7 Professional. Organizations should use AppLocker for all computers that support it.
If you upgrade a computer that uses Software Restriction Policies to Windows 7 or Windows Server 2008 R2 and then implement AppLocker rules, only the AppLocker rules are enforced. For this reason, it is recommended that you create a new Group Policy object (GPO) for AppLocker in environments where both Software Restriction Policies and AppLocker are used.