Like a lot of people, when Microsoft's latest browser was released, I installed it right away. In fact, I installed it on about half a dozen machines. As the days have turned into weeks (soon to be months) since Microsoft released Internet Explorer 7, what has become clear to me and many others is that some Web sites and many Web applications just aren't ready for this new version of the browser. On my computers, that has meant a return to IE6, until the Web and Web-based applications catch up with IE7.

I've received reports from many readers about compatibility problems between IE7 and, especially, Web-based ASP products and proprietary or customized enterprise apps. It's been a five-year run for IE6, and the Web developers who serve the business world appear to have moved in for the long haul.

My best advice at this point is to stick with IE6 for a while if you're a confirmed IE user, or switch at least temporarily to Firefox 2 or Opera 9. If you've made the switch to IE7 and don't want to go back (and I can't blame you -- I prefer IE7 too), the compatibility issues emphasize a key drawback of the new browser you should think through. By upgrading to IE7, you've lost a key safety net that Windows-based Firefox and Opera fans enjoy: They can always fire up IE6 when they hit a site or attempt to run a Web-based app that doesn't react well to their browser. But if you're using IE7, you're stuck.

I talked to Gary Schare, Microsoft's director of IE product management, about this issue. Microsoft has an answer that lets you keep IE6 at your beck and call while you run IE7. I've tested it, and it works fine.

Microsoft made its desktop virtualization tool, Virtual PC 2004 SP1, free for download earlier this year. It's not my favorite virtualization tool, but it works fine.

The key part of the equation is a virtual machine appliance supplied by the IE7 team that consists of Windows XP Service Pack 2 with IE6. It's a 495.8MB download that will work until April 1, 2007. Schare says the IE7 team hopes to renew the program with a new virtual image. There's no charge at all for the use of Windows XP, by the way. This is a pretty good deal.

For more information, check out the Microsoft IE development team's IEBlog: IE6 and IE7 Running on a Single Machine.