HOW TO test a web page in different versions of IE

Pete LePage, an Internet Explorer Product Manager discourages running multiple versions of IE on the same box (he calls them "Frankenbuilds") using tools like IETester.

There 2 good free alternatives for testing your web application in different versions of IE -
For help on using a VPC image, check this step by step guide.

Also see:
HOW TO easily verify your website design in different browsers/OSs