As in the case of the inhouse competition between Windows XP and Windows Vista, due to its prolonged support strategy, Microsoft is also one of its most fierce and stubborn competitors on the browser market. The XP vs. Vista race translates here into the face-off between Internet Explorer 6 and Internet Explorer 7. IE6 has become inherently associated with Windows XP SP2, while IE7 is delivered for XP SP2, Windows Server 2003 and Windows Vista. There was a time when Microsoft referred to the IE7 component on Vista together with a "+" label, but the practice has been dropped.

IE7 was introduced in October 2006 for XP SP2 and in November, 2006 and January, 2007 with Windows Vista. Without a doubt, Internet Explorer 7 is, by all means, a superior product to its predecessor, starting with the graphical user interface and ending up with the security mitigations built into the product. And Microsoft has went ahead and compared the number of fixed vulnerabilities in IE6, IE7 and IE7 in Vista, for the first year on the market.

"Microsoft shipped Internet Explorer 6 SP2 in August 2004 and in the three years since then has fixed a total of 79 vulnerabilities – 50 High / 24 Medium / 5 Low – or an average of about 2.1 per month. Microsoft shipped Internet Explorer 7 in October 2006 for Windows XP SP2 and in November 2006 as part of Windows Vista. In the nearly one year since release, Microsoft has fixed a total of 17 vulnerabilities in IE7 – 14 High / 3 Medium – or an average of about 1.4 per month. Only 14 of the vulnerabilities have affected the Vista release, so that rate is slightly lower," revealed Jeff Jones, Strategy Director in the Microsoft Security Technology Unit.

Just take a look at the adjacent image in order to make an idea of the sheer volume of security flaws impacting the three versions of the browser. From Jones' IE vulnerability counting game it is clear that IE7 in Vista, and IE7 for that matter, is an apex of security for the Internet Explorer line-up of products. "The data indicates that the latest version of Internet Explorer has improved security in terms of fewer vulnerabilities than previous releases, with the Vista version being a bit better than the XP SP2 version," Jones added.