I very very very rarely need a windows install for anything. However - today I needed to talk to something that only has a windows driver.
This got me looking for ways to get a simple virtualized box running - which led me to this github repo: Automated installation of the Microsoft IE App Compat virtual machines
So - first step was simply to install virtualbox (or in my case update it).
Then - all you have to do is
curl -s https://raw.github.com/xdissent/ievms/master/ievms.sh | bash
Or if you want specific IE versions (since this is really for IE testing - e.g. IE7 and IE9):
curl -s https://raw.github.com/xdissent/ievms/master/ievms.sh | env IEVMS_VERSIONS="7 9" bash
More details are on the github page - including info on snapshots (which can help you get around the 30 day limit - just revert to the original snapshot).