I have a Win 7 VM that has a set of CAD/CAM tools than runs my little machine shop. It is more valuable to me than most other data I keep, because I'm pretty sure I can't recreate anything like it. I have a clean copy from shortly after it was created that I re-clone every so often, and it is allowed no network access.

I will be running this VM until I don't care about these machines anymore.

Aside from that and Excel at work, MS still has no other role in my life.