If you have enough space on your hard-disk in your OS-X of Apple, then you could
install virtualbox for Mac-OS-X after download
at http://virtualbox.org
Then you would need "only" 100 GB to create with this virtualbox as virtual harddisk.
Then install for intentions of tests simply for 1 month-free-testtime a Windows of your choice - Vista or 7 or 8 - together with internet explorer ...
You dont need to buy Windows for this as long as you dont test longer than one month - when testing time is expired it is not tragic at all, you simply can repeat a new testing-time ...
This looks trivial but with virtualbox you have a real-time-testing-area in this case with IE - no matter which version of IE !