Like everyone else, I need to test my code on Internet Explorer 6 and Internet Explorer 7. Now Internet Explorer 8 has some great tools for developer, which I'd like to use. I'd also like to start testing my code with Internet Explorer 8, as it will soon be released.
The question is: how to run Internet Explorer 6, Internet Explorer 7, and Internet Explorer 8 on the same machine. So far with Internet Explorer 6 and Internet Explorer 7 I've been using Multiple IE. But people have reported (see comments on the page linked in the previous sentence) issue with Internet Explorer 6 after installing Internet Explorer 8. Those errors are related to focus in form fields. Running Internet Explorer 7 wouldn't matter so much as Internet Explorer 8 can use the Internet Explorer 7 rendering engine, but we still need Internet Explorer 6.
How to run Internet Explorer 6, Internet Explorer 7, and Internet Explorer 8 on the same machine?
Run IE6, IE7, and IE8 on the Same Machine Using Windows 7 XP Mode
http://articles.sitepoint.com/article/ie6-ie7-ie8-win7-xp-mode
I use http://www.spoon.net/browsers (Windows-only).
You can run IE8, IE7, IE6, Firefox 3.5, Firefox 3, Firefox 2, Safari 4, Safari 3, Opera 10, Opera 9, Chrome.
You just need to install a plugin, and then click on the corresponding icon. It will download and run the files needed to run each of the above mentioned browsers.
Use Internet Explorer Application Compatibility VPC Image.
Download it from Microsoft Download Center link
Backing up the other users, you will need to run Virtual PC instances on your Windows box. If you try to do a multi install of Internet Explorer, you will break conditional comments on pages, which will make testing difficult anyway (For example, With Internet Explorer 5, 6 and 7. On a Windows box, the IF Internet Explorer statements will resolve to Internet Explorer 7 even in Internet Explorer 5, which means even more weird bugs.
More information and a link to download and run a Internet Explorer 6 Virtual Image: http://blogs.msdn.com/ie/archive/2007/04/17/ie7-virtual-pc-image-and-ie6-virtual-pc-image-refresh.aspx
If you have Virtual PC already, here is the image: http://www.microsoft.com/Downloads/details.aspx?FamilyID=21eabb90-958f-4b64-b5f1-73d0a413c8ef&displaylang=en
Very good option is update to Internet Explorer 10. You will find very useful developers tools including compatibility with from IE5 to IE 10 including quirks mode. If switch the IE version i menu, the page rendering of the page is changing immediately.
Very good feature of this mode is javascript and HTML (firebug like) debugger, which works in compatibility mode. It means, you can debug javascript in very old IE with the newest debugger, which is very cool feature. You cannot do that with virtual machine. Yes, you can have virtual machine for checking the final result.
Somewhat related, you should consider running your site past BrowserShots when it is almost done, see how it looks in dozens of browsers on hundreds of configurations.