Vista - Outlook as email client in Vista Home premium

I purchased a laptop with Windows Vista Home Premium and have installed Microsoft Office 2000 including Outlook. When I go to "set default programs" for inteinternet services Outlook does not show up as a choice. How do I set Outlook as my default email client? I will admit I am not familiar with "Windows Mail". Is it better or is there a reason I should use it as opposed to Outlook? I don't use Outlook for calender or those types of things. I use ACT! as my contact manager. I can put my ACT! email address book in Outlook. Thanks for your help.