Most of the popular browsers these days are based on one of the two open source rendering engines - khtml/WebKit and Gecko. The most popular browser, however, is based on proprietary technology: Internet Explorer. Even though IE made some progress during the past few years, it's no secret that it took Microsoft far too long to counter the success of Mozilla's Firefox. Currently, Microsoft is working (and thus, spending money) on Internet Explorer 8, and this prompted an audience member during a keynote by Steve Ballmer to ask an interesting question: is it worth spending money on IE, with so many open source engines readily available? Ballmer's reply may surprise you.