Microsoft, laucnched a website called "Modern IE", in which you can find many things :
- Web page scanning and validation
- Virtual tools, more below
- Best practices
- and other stuff to get IE10 and follow news on IE10.
So as for today, with VirtualBox, you can test IE7 to IE10 from Windows Vista to Windows 8.
No excuse from now about not testing your site on most browsers.