Found my own answer at:
http://docs.info.apple.com/article.html?artnum=151247
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Making Safari your default web browser
You can make Safari your default browser. If you do, Safari opens when you
click a link in a document, such as a Mail message, or double-click a Web
Internet Location file in the Finder.
Safari is set up to open these pages in a new window, but you can select to
open them in a tab in the current window.
Choose Preferences from the Safari menu, then click General. Choose Safari
from the Default Web Browser pop-up menu.
Select the "Open links from applications" option you want to use. If you
select to open pages in the current window and you select Enable Tabbed
Browsing in the Tab pane of Safari preferences, then pages open in a new tab
in the current window.
If you click a link in some programs, the program may open the webpage in a
browser different from your default browser.
