eldavojohn writes "According to Google, Microsoft's server software is at least twice as likely to host viruses or malware. The reason why? 'Google reports that IIS is likely used to distribute malware more often than Apache because many IIS installs are on pirated Windows versions which aren't configured to automatically download patches. (Even pirated Windows versions can automatically receive security fixes, however.) Our analysis demonstrates how important it is to keep web servers patched to the latest patch level,' Google notes."