Microsoft announced Thursday that it is making available the first release candidate of Internet Explorer 7, and it says it expects to quickly progress towards a final launch during the fourth quarter of this year.

Although Beta 3 was feature complete, RC1 includes some additional enhancements mainly under the hood. The new browser runs on Windows XP SP2 and Windows Server 2003.

Although the initial IE7 release candidate would be available only in English, the company expects to have localized versions in Arabic, Finnish, German and Japanese by September. In addition, RC1 will bring French and Spanish versions for the first time. The final version of IE7 will include 35 localizations, the same number offered in Windows.

IE7 notably adds a tabbed interface and improves on browser security. Microsoft has also built into the browser an RSS platform that provides a framework for downloading, storing and accessing RSS feeds across the Windows operating system.

Other enhancements include a simpler user interface, customizable search box, reworked favorites organization, and enhanced accessibility for people with disabilities. Under the hood, CSS improvements and transparent PNG support catch the browser up to rivals such as Firefox, and native support for XMLHTTP means AJAX-based Web applications will no longer require an ActiveX control to function.

RC1's main goal is to assist developers in ensuring that their Web sites are compatible with this impending update to Internet Explorer, Cobb said. "We're confident code that works in RC1 will be compatible with the final version," she explained.

On the subject of CSS, Cobb admitted that IE7 was still a work in progress. However, the IE team had worked to address two major issues, one concerning maximum/minimum height and width image issues, along with a bug that caused whitespace in list items.

To ease upgrading from previous versions of IE7, Cobb said RC1 also adds an uninstall feature, which would automatically remove any earlier beta releases of the software. In the past, testers would have to manually remove IE7 via Add/Remove programs.

Microsoft is very confident in this latest version of IE7, with Cobb saying she didn't see a need for a second release candidate. Still, she acknowledged that, "it all depends on feedback on RC1." Cobb would not commit to a more solid launch date other than saying that she was confident that the browser would ship in the fourth quarter.

For those using IE7 through Windows Vista, enhancements in RC1 would likely make it into the next public build of the next-generation operating system, along with under the hood improvements to Vista-specific IE7 features, Cobb revealed.

Internet Explorer 7 RC1 can be downloaded from FileForum for Windows XP SP2, Windows Server 2003, and x64 Editions of Windows. Try it out and tell us what you think below!