Though the Macintosh version of Internet Explorer isn’t the danger that its Windows counterpart is (it’s a separate code base and it’s not part of the operating system, with all the vulnerabilities that entails), it isn’t being actively developed and is increasingly out of date. Using it isn’t computationally suicidal (as using Internet Explorer on Windows is), but it’s hardly ideal. Fortunately, OS X includes Safari, which is a much better browser, but unfortunately, not every Web site works properly with Safari. There are fewer and fewer sites that don’t, but it still happens.
For those Web sites that don’t work with Safari, I use Mozilla‘s Camino, of which a new version has just been released. There are other excellent alternative browsers available for OS X, including Opera and Mozilla’s Firefox. The choice between Opera and the Mozilla browsers is a matter of personal taste, but of the Mozilla browsers, Camino, which is OS X only, integrates into OS X more seamlessly than Firefox–almost as seamlessly as Safari, in fact. So if you’re using a Mac, you may find Camino a handy tool to have installed.