Good review of IE9 over at Arstechnica: http://arstechnica.com/microsoft/reviews/2011/03/the-most-modern-browser-there-is-internet-explorer-9-reviewed.ars
Once again, MS screws up it's own product strategy: "It's also a little disappointing that the 64-bit version is less polished than the 32-bit version. It can't be made the default browser, and it doesn't include the new, high-performance scripting engine. Microsoft has long argued that 64-bit browsing isn't necessary; most plug-ins are only 32-bit, and so, the argument goes, browsing must be a 32-bit activity. This is unfortunate. One, it leads to a certain chicken-and-egg problem: there's little incentive to develop 64-bit plug-ins since nobody uses a 64-bit browser due to the lack of plug-ins (though Adobe Flash 11 is likely to include first-class 64-bit support, resolving one of the big stumbling blocks). Making the 64-bit version first-class—the same features and performance as the 32-bit version—and ensuring that, at least, Microsoft's own plug-ins (such as Silverlight) were supported would go a long way towards making 64-bit browsing viable. This is, after all, much the same route as the company took with Office." And there are good reasons why you would want to run the 64-bit version: "The reason that 64-bit is desirable is particularly because it offers the potential to strengthen certain anti-hacking mechanisms. Address Space Layout Randomization (ASLR) depends on the ability to change the in-memory layout of things like DLLs. In a 32-bit process there are only a limited number of random locations that can be chosen. 32-bit processes are also more vulnerable to anti-ASLR measures such as "heap spraying" (wherein a large proportion of the browser's memory is filled with malicious code to make it easier for an attacker to trick the browser into executing it). 64-bit is by no means a panacea, but it does strengthen these protection systems. For something that is as frequently attacked as a Web browser, this kind of defense in depth is desirable." Unfortunately, if you're running 64-bit Windows, you can't install the 32-bit version. You're stuck with the 64-bit version, which means no scripting performance improvement and far fewer plugins. Which means I'm sticking with Chrome. --- Brian
