For a long time now, I've been using
Tredosoft's Multiple IEs. It's a great little package that allows you to run multiple versions of IE on the same machine, from IE 6.0 all the way back to IE 3.0! Okay, now no one is running IE 3.0 any more (I hope!) but from time to time, people want IE 5.5 support (still! yes, I know!) and certainly IE 6 is, unfortunately, still being used. Before I found the Multiple IEs package, I was considering running several virtual machines, each with a different version of IE installed.
