Microsoft is one big reason why I've been playing with alternatives for years! Mac, (H)ac, and all varieties of *nix have been very viable options for years. I had Ubuntu on several of my machines for some time.

Now, I run OS X.7 on 3 of my 5 machines. 1 is on Win7 and the netbook used be Ubuntu, now switched to WinXP due to driver necessity (that's actually relative but I just don't have the Sk!llZ to roll my own) for my 3G dongle.

There are plenty of M$ alternatives. I do however have to use MS Office due to my freelancing work. OpenOffice and LibreOffice are CLOSE but juuuust don't quite cut it.