The latter is the most mysterious of all. It is an imponderable mystery how anyone can reach the conclusion that Microsoft’s average response time between discovery of a flaw and releasing the fix for that flaw is superior to that of any competing operating system, let alone superior to Linux. Microsoft took seven months to fix one of its most serious security vulnerabilities (Microsoft Security Bulletin MS04-007 ASN.1 Vulnerability, eEye Digital Security publishes the delay in advisory AD20040210), and there are flaws Microsoft has openly stated it will never repair. The Microsoft Security Bulletin MS03-010 about the Denial Of Service vulnerability in Windows NT says this will never be repaired. More recently, Microsoft stated that it would not repair Internet Explorer vulnerabilities for any operating systems older than Windows XP. Statistically speaking, seven months between discovery and fix might not have an overly dramatic effect on the average response time if you can find enough samples of excellent response times to offset anomalies like this, assuming they are anomalies. But it only takes one case of “never” to upset the statistical average beyond recovery.