We have evaluated the following options for Multi Browser Testing with more focus on IE but covers 200 other browser versions.
Freeware : Used in the past
Can test up to IE 10. Currently lots of open bugs which can affect production level applications.
Recommendation: Can ignore for enterprise / production level applications.
Browser based (paid subscriptions) : Completed a demo test and recorded the video.
Can test every single browser available and mobile / tablet platforms as well.
Recommendation: Good for an enterprise license as we have test capability for multiple OS, multiple browser versions and covers website + mobile + tablets. But paid.
User guide and release notes - https://modernievirt.blob.core.windows.net/vhd/virtualmachine_instructions_2013-07-22.pdf
Works on Virtualization principle and apparently can be a VM on a VM. While there are around 5 virtualization solutions (Hyper V, Virtual PC, VMWare, Virtual Box & Parallels). I have completed the test with Microsoft’s Virtual PC.
I tested running windows XP and IE 6 on my laptop and was able to browse through and run the test successfully.
Recommendation: The BEST for testing IE versions on different OS flavors available today, free and easy to set up and run.