With all of the viruses, worms and Trojan horses using Microsoft's Internet Explorer and Outlook exploits to take control of your computer, I feel that the safest way to use the Internet is NOT to use Internet Explorer and Outlook. I like Mozilla Firebird as an Internet Explorer alternative, and Mozilla Thunderbird as an Outlook alternative.
I have been using the Mozilla Firebird browser for about a year and have found it to be the best alternative to Internet Explorer. The pop-up blocker is wonderful, and once you use tab browsing, you'll never want to be without it. The integrated search feature is another great time-saving feature. You can find more options for the search bar at Mycoft. The following is taken from the Mozilla Firebird webpage:
Mozilla Firebird is a speedy, full-featured browser that makes browsing more efficient than ever before. Firebird includes:
...and a number of other details that work together with you to help you get the most out of your time online.
For a really good, in-depth description about the benefits of switching to Mozilla Firebird, checkout "Why You Should Switch to the Mozilla Firebird browser" written by Ben Goodger.