Which they do, they've been offering complete VM images with various combinations of Windows and IE for some time, the current offering is XP + IE6, Vista + IE7, Win7 + IE8 and Win7 + IE9: http://www.microsoft.com/en-us/download/details.aspx?id=1157...
While the images are for VirtualPC, I've yet to have any issue importing them in VMWare or VirtualBox.
> IE8 made some improvements to JS debugging (SOME) and is vastly better than 6 and 7. IE9 might be amazing, and IE10 might be the best browser in the world - I don't know. All I know is that debugging IE takes almost as long as building the application did in the first place.
IE9's devtools are significantly better than IE8's: more feature and much more stability. They are nowhere near WDT/Firebug yet (or even Dragonfly), but they are a huge improvement over the POS that IE8's devtools are.