How to install multiple versions of Internet Explorer on your PC
But if you're a developer and you want to see how your website looks to someone running an ancient browser, you might want to install an old copy of Internet Explorer alongside your IE7. And it turns out that this is completely doable if a little complicated. You need to alter some settings, redirect some DLLs, and rename a few things here and there.
Or you can just download the installer Yousif Al Saif created. It will install Internet Explorer 3, 4.01, 5, 5.5, and 6 on your PC. You'll probably want to make sure you're already running IE7 when you begin. The installer will not work with Windows Vista, but if you've got Windows XP, you can be the first on your block to run 6 different versions of Internet Explorer. Your neighbors will be so jealous.