From your various posts I deduct that you are an IT "professional" who does a bit of programming on the side when the need arises. I believe that most of the computers that you oversee in your capacity as an IT "professional" are Windows based.
I work as the security architect for one of the largest internet security companies in the US with government and intelligence agencies from all over the world as customers. Since I am not speaking for my company I will not mention its name.
My company works closely with MS and all other OS and software vendors to help make systems more secure. MS has made great strides toward becoming more secure in the past year or so. Having said that, open systems have the ability to be much more secure than closed systems for all of the reasons already mentioned on this thread.
I can find you hundreds of articles/papers from private and government sources that show why security through obscurity does not work.
Here is one http://slashdot.org/features/980720/0819202.shtml
Do a quick search on google and you will find many more.
If I were an executive at the company where you work I would be concerned with the security of your network if someone like you made the security decisions. People with your line of thinking tend to leave portions of the network vulnerable because "how is anyone ever going to find out about this phone line connected to this machine behind my firewall?"
Sorry, but I certainly know enough about the industry to immediately classify any links to hacker hangout "slashdot" as questionable. Members of that "community" routinely posts anti-American rhetoric as well as completely false and misleading information, ultimiately making the Linux campaign that arrises from there primarily one of disinformation.
I know who Bruce Perens is, and went ahead and read your piece, but found it to be nothing more than an attack on proprietary code based on a flaw that exists within his OSS products as well - the fact that not all vulnerabilities are reported.
Somehow though, he can't seem to come to grips that by publishing his entire source code contents make this even more likely to happen in open source products, especially when he continues on to make the unsubstantiated claim that his peer review model of volunteers can successfully scale with a growing code base that becomes widely utilized.
Please take your personal attacks back to slashdot, where you people can continue to group speak and attack and mod down those who actually know about computer security from experience in DoD environments or other large scale business enterprises, who rarely waste their time there.