I do in-house web sites for a living. We do NOT support Internet Explorer. Why not? Because we can't affort to install virtual computers running legal versions of Windows XP, Windows Vista, Windows 6 (?), Windows 7, Windows 8, and Windows 9. We just tell our people to use Firefox; it's availlable for free for anything.
Giving away copies for compatability testing would be a great idea.
(Neither can we affort a back room full of old MAC's, but I can test Safari on Windows XP and haven't run in to any problem yet.)