Microsoft has released the first release candidate for its coming Internet Explorer 9 web browser. IE9 is a major overhaul, bringing much needed speed improvements, better support for web standards, privacy controls and tighter integration with Windows 7.

Overall IE9 RC1 is a huge leap forward for Microsoft, embracing web standards and speeding up the browser. When IE9 is released web developers will finally be able to stop using CSS hacks and start using HTML5 with more confidence. Of course IE8 and IE7 will still be with us for some time to come, but things are looking up.

Curious developers running Windows can download the release candidate from Microsoft. This version of IE9 expands support for semantic HTML5 elements (like <nav>, <section> and <article>), adds more CSS 3 properties and introduces support for the geolocation API.

The additional geolocation support rounds out Internet Explorer’s new HTML5 features. While IE9’s competitors have implemented some of the more experimental APIs (like Web Workers and offline cacheing), IE9 does close the feature gap considerably and is leaps and bounds beyond where IE8 left off.

When it comes to CSS 3 the new IE offers nearly full support, though it still doesn’t understand text-shadow (which is actually been around since CSS 2.1) or the new CSS 3 multi-column text layout tools. On the bright side, IE9 does render border-radius, 2D transforms and new CSS 3 selectors like :first-of-type. For a full rundown of IE9’s HTML5 and CSS 3 features, see our earlier coverage. Also, be sure to head over to the IE9 Test Drive website for some demos that show off IE9’s new standards support.

IE9's CSS 3 support handles border-radius rules

The new IE9 release candidate adds some privacy controls similar to those Mozilla and Google have been adding to their browsers. IE9 will support the Do Not Track HTTP header [Update: Microsoft says that IE9 does not support an HTTP header at the moment, but does offer Tracking Protection Lists which can block cookies, beacons, pixels and more]. IE9 also supports cookie-based blacklists to stop advertisers from tracking your movements around the web.

If you’ve been using the beta releases of IE9, you’ll notice several changes to the look of IE9, including the ability to put tabs back in their own row, rather than next to the address bar, which is the default setting. To give your tabs a bit more breathing room, just right click on the tab bar and select the “Show tabs on a separate row” option.

Top: the default tab arrangement; Bottom: tabs in their own row

This release also adds a new security feature which allows you to turn off ActiveX for all sites and then re-enable it on a site by site basis. ActiveX, a Windows-only “enhancement” that allows webpages to install code on your PC, has long been an excellent way to load up your Windows machine with viruses and other malware. The new controls mean you can turn off ActiveX entirely and avoid malicious code being installed.

Microsoft is also touting IE9’s hardware acceleration improvements in this release. According the IEblog, the release candidate is 35 percent faster than the previous IE9 beta. Indeed, in our informal testing IE held its own with Firefox 4 and Chrome 11. Pitted against stable releases like Firefox 3.6 or Chrome 9, IE9 fares even better.

Microsoft has not yet set an official release date for IE9, though the company’s web-centric MIX conference, which starts April 12, has historically been host to major IE announcements.

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