You can make a difference on your personal security by using the right browser. There has been a lot of debate which one to use since Microsoft's Internet Explorer seems to let everybody use your computer by exploiting the security holes. Experts seem to recommend Mozilla's software. Personally I think this is a matter of personal preference and some are just happy because the word "Microsoft" is missing from the browser they're using. The fact is that the same holes are found from almost each browser, it's just that the Internet Explorer doesn't get updated as often as it should to fix those. A good browser has an pop-up blocker, increases your security and makes the Internet a much pleasant place to be by blocking the annoying ads. Always keep such software up-to-date!
Internet Explorer, Microsoft, free (bundled with Windows operating system)
Personally I use this one. With Service Pack 2 update it contains the pop-up blocker. Good all-rounder I think, most of the pages in the Internet are designed to this browser. Ensures good compatibility with pages.
Firefox/Mozilla, Mozilla, free!
Firefox is little lighter than the Internet Explorer, offers all the same features. Mozilla comes with capabilities to read email, news, IRC etc. Updated frequently. Excellent choise if you don't want to use the Internet Explorer.