On Thursday, Microsoft released Microsoft Internet Explorer (IE) 7.0 Release Candidate 1 (RC1) for Windows Server 2003, Windows XP, and XP Professional x64 Edition. This final development milestone doesn't include any major new features but improves the fit, finish, and overall quality of the product. It's available to the public for free.

"IE 7.0 RC1 is a more polished and refined product," Tony Chor, a group program manager on the IE team, told me during a recent briefing. "We're still on track for Q4 2006 release."

RC1 does incorporate feedback Microsoft received in the wake of the Beta 3 release by automatically uninstalling previous versions of the IE 7.0 beta so users don't have to do so manually. It also includes some small UI changes and other fit and finish improvements and provides better performance than its predecessors.

Microsoft has also been working to improve IE 7.0's compatibility. The browser works in two modes, Chor told me. The first, dubbed Quirks Mode, is the default: This mode emulates the rendering engine from IE 5.0 and 6.0 and provides the best compatibility with existing Web sites. The second, called Standards Mode, or Strict, is Microsoft's best standards-based implementation, Chor said. Web sites can add code to their sites to ensure that visitors using IE 7.0 view the site using Standards Mode. Microsoft has also been working with Web site designers to ensure that their sites are compatible with IE 7.0.

Interested users can find out more about IE 7.0 RC1 and download it from http://www.microsoft.com/ie/ie7.