Control Panel | Add/Remove Programs | Set Program Access and Defaults.
And in IE: Tools | Internet Options | Programs.
Outlook and Outlook Express are entirely different programs. You will get
better help in an MS Outlook newsgroup:
news://msnews.microsoft.com/microsoft.public.outlook
news://msnews.microsoft.com/microsoft.public.outlook.General
news://msnews.microsoft.com/microsoft.public.outlook.configuration
news://msnews.microsoft.com/microsoft.public.outlook.installation
news://msnews.microsoft.com/microsoft.public.outlook.Contacts
news://msnews.microsoft.com/microsoft.public.outlook.Calendaring
news://msnews.microsoft.com/microsoft.public.outlook.Fax
news://msnews.microsoft.com/microsoft.public.outlook.interop
news://msnews.microsoft.com/microsoft.public.outlook.printing
news://msnews.microsoft.com/microsoft.public.outlook.Program_AddIns
news://msnews.microsoft.com/microsoft.public.outlook.program_forms
news://msnews.microsoft.com/microsoft.public.outlook.Program_VBA
news://msnews.microsoft.com/microsoft.public.outlook.ThirdPartyUtil