One day, around seven years ago, I clicked some wrong link and my Windows (XP, iirc) went full retard. As I know that you cannot trust an operating system once it was compromised, I decided to fire up a GNU/Linux live CD to rescue whatever data I can.
Short before I was about to go through the hassle of reinstalling my Windoze, just to maybe have it infected again (which would be my very second time of ever having an infected system), I thought about whether a GNU/Linux system could replace my old Windoze at home as well as at work.
Since then, I'm 100% GNU/Linux and infection free.