If every computer had antivirus software running, life would be tough for bot herders and cyber crooks. Their ability to orchestrate spam campaigns and denial of service attacks relies on a plentiful supply of unprotected computers. Windows 8 will put the squeeze on those creeps. It has antivirus protection built right in, enabled by default if no other antivirus is present. But the new security features at the very deepest level may be even more significant. To understand what Windows 8 adds, we need to look back at the evolution of operating system security.