A number of well-known information security specialists have written an opinion on the security risk resulting from Microsoft's monopoly.

"Most of the world's computers run Microsoft's operating systems, thus most of the world's computers are vulnerable to the same viruses and worms at the same time. The only way to stop this is to avoid monoculture in computer operating systems, and for reasons just as reasonable and obvious as avoiding monoculture in farming."

The authors recommend government intervention "to confront the security effects of monopoly and acknowledge that competition policy is entangled with security policy from this point forward". They also have a few short-term recommendations for Microsoft such as publication of certain specifications.

One of the authors, Daniel Geer, Chief Technical Officer for @Stake, was fired because of the report. @stake said that Geer had been sacked because he had not gained its approval for release of the report, which presented opposing views to those of the company.

CyberInsecurity: The Cost of Monopoly
http://www.ccianet.org/papers/cyberinsecurity.pdf