LINUX. *grin*. At least a decade of use with absolutely no viruses, rootkits, adware, or any other type of malware whatsoever. (actually more than a decade but no bloody way I will ever post exactly what I use or possess on any online site or email. S'truth!
I used to use knoppix from a cd with no hard drive for my home use.
At work, we used a lot of CentOS/Redhat for servers.
We ran windows on VMs. Just click reset and the problems go away.
Linux is not completely secure either. Although, I agree that it tends to be more secure than windows.