Microsoft has officially released the final version of Internet Explorer 9 for Vista (32-bit and 64-bit) and Windows 7 (32-bit and 64-bit). After years of haemorrhaging market share to rival web browsers like Firefox and Google Chrome, Microsoft feels it finally has a browser capable of fighting back.

Internet Explorer 9 has been in the wild for around six months now, first as a public beta, and then as a Release Candidate. That means its feature set is well known, and as the RC was feature-complete, the new release contains nothing that isn’t already known to those early adopters who installed the Release Candidate on February 23rd.

Microsoft would like Internet Explorer 9 to be known as fast, clean and trusted. The emergence of the beta version shook up rival browsers with its speed, helped immeasurably by drawing on the computer’s graphics chip to provide hardware acceleration for graphics-intensive tasks like online gaming and video streaming. Both Firefox and Chrome were quickly forced to follow suit in order to prevent IE9 from opening up a significant performance gap.

The interface for IE9 is also radically different from its predecessors, boasting a streamlined designed to maximise the amount of screen space for displaying websites. Firefox 4 has also been designed in a similar way, while both must tip their hat to Google Chrome which pioneered such a minimalist user interface. Tabs can also be “torn” off the main IE9 window, allowing two or more websites to be compared side-by-side (Windows 7 users will gain most from this feature in conjunction with Aero Snap).

There’s a new Download Manager tool that allows you to both pause and resume downloads, plus provides additional protection against malware by comparing the downloaded file to a database of known trusted files – if the file isn’t on this database, you’ll be warned that it’s suspicious.

The new Add-Ons Manager is also geared towards performance, with an Add-Ons Performance Advisor letting you know which add-ons are responsible for slowing IE’s boot time. One major new feature introduced in the RC was Tracking Protection, which is designed to prevent websites from tracking your browsing – it can be found under the Safety menu, while other changes from the beta releases included performance and usability improvements, plus better support for HTML5 standards.

Internet Explorer 9 is available now for both Windows Vista (32-bit and 64-bit) and Windows 7 (32-bit and 64-bit), and should soon appear as an option in Windows Update as well as a separate download – regardless of whether or not you use Internet Explorer as your primary browser, it should be considered an essential update. Windows XP users will have to stick with Internet Explorer 8 or consider switching to an alternative web browser.