Alert the antitrust police. Microsoft is back to doing it again: taking advantage of its dominant position in personal computers to benefit its Web browser. It's blatant. And it's terrific.

Internet Explorer 9, available in beta, or test, form this week, is the best browser Microsoft has ever produced. If that isn't saying much, this says more: It may turn out to be the best browser for Windows that anyone has produced.

And that's saying quite a lot, given the proliferation of top-notch browsers: Mozilla's Firefox, Google's Chrome, and even the Windows version of Apple's Safari. Indeed, it's a mark of how much the digital world has changed that nary a regulator's eyebrow was raised by aspects of the new Internet Explorer that might have set off alarms a decade ago.

IE9 isn't for everyone; in fact, it isn't even for every Windows user. The browser, which is available as a free download, doesn't work with Windows XP, the 9-year-old operating system that remains the most widely used version; it is compatible only with the more recent Vista and Windows 7 flavors.

Particularly with Windows 7, the new browser blurs the distinction between Web content and applications that run on your PC. You can now pin website icons to the Windows task bar, where they look and act just like the programs on your local hard drive.

The new software also goes well beyond its competition in taking advantage your hardware. By and large, most browsers tap very little of a machine's raw computing power, such as the potent graphics chips found in modern PCs. IE9 uses the PC's hardware to provide a speed boost.

Now a lot of other factors besides the browser affect how fast the Web feels to you - such as the quality of your Internet connection and the design of the site you're visiting.

Still, the browser is an important piece, and IE9 is demonstrably faster than its predecessor. With this browser, Microsoft is also embracing HTML5, the same online-graphics standard that Apple's Steve Jobs has been touting as a faster, better alternative to Flash.

Microsoft even extends its quest for speed to the length of time it takes to launch Explorer. If you have a third-party toolbar installed - say, the one from Microsoft's arch-nemesis Google - IE9 will tell you just how much it's adding to your start-up time, and encourage you to disable it. If you still want to conduct searches directly from the browser, don't fear: Explorer now lets you type a search term right into the address bar, a feature Chrome has had for some time.

Visually, the new browser is almost minimalist. Microsoft has cut down on the buttons and menus visible by default. Messages and dialogue boxes that used to appear in the middle of the browser window, disrupting content, have moved to the bottom.

The net effect - no pun intended - of all Microsoft's changes is a browser that is thoroughly clean, fast and modern, attributes that haven't always been attached to Internet Explorer. If the new software can also avoid the security lapses, Microsoft will be able to claim that its No. 1 market share isn't just because of who makes it.