Andy Tanenbaum, the author of the MINIX operating system, recently posted an opinion piece on the origins of Linux. It's a fascinating albeit somewhat lengthy read -- see http://www.cs.vu.nl/~ast/brown/ for the full text.
At the very end of the document, he talks about the security of a microkernel system like (his own) MINIX vs. that of a monolithic kernel like Linux. He writes, "With all the security problems Windows has now, it is increasingly obvious to everyone that tiny microkernels, like that of MINIX, are a better base for operating systems than huge monolithic systems. Linux has been the victim of fewer attacks than Windows because (1) it actually is more secure, but also (2) most attackers think hitting Windows offers a bigger bang for the buck so Windows simply gets attacked more. As I did 20 years ago, I still fervently believe that the only way to make software secure, reliable, and fast is to make it small. Fight Features." Cheers, Ken -- KRvW Associates, LLC http://www.KRvW.com