Install multiple versions of IE on your PC
Ever wanted to test your website in various versions of Internet Explorer?
Every time you install a newer version of Internet Explorer, Windows has a tendency to overwrite previous versions. And generally, that's a good thing. You're missing out on an awful lot if you're using Internet Explorer 3 to browse the web these days. AJAX, Flash, and other newfangled features just aren't going to work as well, or at all.
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.
If you have a PC running Windows XP (it doesn't work for Vista) and you want to test your application in multiple versions of Internet Explorer, you need to install this software.