Establishing Group Policies for Outlook 2007
By default, the group policy does not contain any Outlook 2007 specific settings that you can use to lock down Outlook’s configuration settings. Microsoft does however offer a set of administrative templates for Office 2007 (of which Outlook is a part) that you can download for free from Microsoft's site. You can then use these administrative templates to add Outlook specific settings to the group policy.
Download outlook 2007 administrative templates: