I came across this link today while reading a blog post from Mark W. Breneman. IE NetRenderer allows you to check how a website is rendered by Internet Explorer 7, 6 or 5.5. This service points out that they can stand above the rest processing many requests at one time meaning no line to wait in for you which is always nice. In addition to being able to check specific versions of IE you can also check them in mixed and difference mode. This allows you to see how the 2 version of IE render it differently. Here are the difference and mixed mode screen shots i took about 10 minutes ago. This is very helpful seeing how you can not install both version of IE on 1 machine, at least not easily. In my case there a couple things off and probably due to a padding or margin difference but no major problems.
difference


mixed