With the release of IE9 I have seen a number of both internal and external questions about the product so I thought I would come up with a quick FAQ about some of these questions.
I run 64-bit Windows, should I download the 32-bit version or the 64-bit version?
You should download the 64-bit version. When you install the 64-bit version of IE9 the 32-bit version is also downloaded. The 32-bit version is the Operating System default even on 64-bit versions of Windows. This has been the case since Windows XP 64-bit and IE6 (yes there was a 64 bit version of IE6). There are a number of reasons why 32-bit is the version you will be running (mostly because only 32-bit add-ons like Flash and Silverlight don’t work in 64-bit) but if you want to get the details see this blog post from the product team.
I develop web sites and need to test against multiple versions of IE, can I run IE9 side by side with prior versions?
No. You can only have one version of IE installed. However there are a number of ways to support your needs. Within IE there are a set of developer tools that can help you understand how your site will be rendered in IE9 and prior versions. Go into your site with IE9 and hit F12 and you will see tools to change Document Mode (rendering engine) and Browser Mode (user agent string sent to the server).
If you are really serious about testing I recommend Expression Web SuperPreview. This tool will allow you to test IE6, IE7, IE8, IE8 in IE7 Compatibility Mode, and IE9 renderings (against each other or against a reference rendering). For IE testing the tool is completely free. You can also use this tool for testing against Firefox, Chrome, and Safari but a license for Expression Web is required (which you may have as part of your MSDN subscription).
Will IE8 add-ons (Web Slices, Accelerators, Search Providers) still work?
Yes, the add-ons that worked in IE8 work great in IE9. I know that I use the Wikipedia accelerator all of the time, it is one of my favorites. And the Bing Translate accelerator has been great to use while watching the news of the recent tragedy in Japan. If an end-user adds a Web Slice the Favorites bar will appear so the slice is visible.
Should I upgrade to IE9?
If you are running IE8 you should absolutely upgrade to IE9 (and are running Windows Vista or Windows 7). It is more secure and faster than IE8. There is plenty of coverage out there around pinning and jump lists (hint, drag the Facebook URL to the Taskbar in Windows 7 and you will see it in action).
If you are using Firefox or Chrome (or something else) as your primary browser on Windows Vista or Windows 7 I would encourage you to upgrade to IE9 anyways and give it a try. IE is often embedded in other apps and you should have the fastest and most secure browser on your operating system.
If you are still on Windows XP, you should upgrade to a newer version of Windows. Windows XP is a ten year old operating system. There have been newer versions of Windows available for over four years and there hasn’t been a major service pack in over three years.
Once I upgrade can I go back if I need to?
Hopefully you don’t want to go back, but if for any reason you need to revert to a prior version you can uninstall IE9. To uninstall you need to go into Programs and Features and then select “View installed updates” on the left. Under the Windows category you will find an entry for Windows Internet Explorer 9