I mentioned that you can indeed install multiple versions of IE on one machine. Microsoft has recently made Virtual PC 2004 a free download; we’ve taken advantage of that by releasing a VPC virtual machine image containing a Windows XP SP2, IE6 or IE7 or IE 8 this will help facilitate your testing and development.
Get more information on Virtual PC 2004
Download Virtual PC 2004
Download the Internet Explorer ALL Testing VPC Image
Tredosoft provides an installer that does everything you need to get that for IE3 IE4.01 IE5 IE5.5 and IE6. They also provide a standalone installer for IE 7.
First way I tested and It was very helpful for my web development works.