They are trying to force people who develop websites for IE (which applies to 95%) to buy a copy of windows.
It appears as if the IE exe's made by Xenocode still work. I don't have a link for them, I'm not sure if they're hosted anywhere still.
You may also want to check out http://shapeshed.com/journal/testing_with_ie6_ie7_and_ie8_on... if you wish to use virtualbox rather than paying for virtual PC