So, I move to Open Office (spreadsheet and wordprocessor for 90% of the office), make my server FreeBSD (solid as a rock), write my aps in Java or PHP with Mysql in the backend, and when the big crash happens, my little world just keeps on going. What a relief. And all the software is free.
So, I take a hit on the learning curve of Unix (which is not negligible), but the application changeover won't be too bad if done over a few years and I've already started that. So, all in all it comes out about the same costwise over say 5 years, but I'm way ahead on the catatrophic failure front and not having to worry about the next killer virus. And over 20 years there's no planned obsolesence to pay for (needed to keep Microsoft in Business)