I've got some layout problems with internet explorer and situations leads me to test the site under different versions of Internet explorer but trust me it's not a easy job to run internet explorer 4, 5, 6 and 7 in the same system. But hey there are always solutions.. Tredosoft has came up with the installer which will run internet explorer from version 3 until 7. Thats a impressive piece of work. Ever wanted to test your website in various versions of Internet Explorer? It is possible to run Internet Explorer in standalone mode without having to over-write previous versions thanks to Joe Maddalone who came up with a way of achieving that in November 2003. Basically, Internet Explorer is run by exploiting a known workaround to DLL hell – which was introduced in Windows 2000 and later versions – called DLL redirection.
TredoSoft has another beautiful article on Internet Explorer 7 to run it in standalone mode . You might want to check it out.