I think that this article in The Register gives a wonderfully concise summary of all the "why Linux is more secure than Windows". Although the article talks solely about viruses, it is equally applicable in other areas.

Read it here.

i enjoyed that article, thanks for posting it
also, when you click the link in the article to go to the page about how there will be more viruses in linux is absolutely worth it when you see quotes like ::
and
pure genious haha....as of the first quote, well i am speechless....period...

and as of viruses i know i could/did write a virus(es) in windows and it took roughly a half hour (of course it was nothing that could bring the world down) but in any case lets just say you had to re-install windows if it executed...
i know there isn't too many (maybe a handful) of people around that could accomplish this on linux, under normal circumstances....unless a simple virus was made and executed on a persons machine that is logged in as root...
but then again lets not label "easier" as the amount of time it takes one to make the virus, but take into consideration the exploits...and in a personal opinion, windows wins in this field cause in any case with bugs/exploits in linux, you usually will have the fix by the following day, or at an extreme within a week.... in windows you'll have to wait a couples months for service pack 73 to be added to their site....
so imo, if you do click to read that site which is linked in the original article, i wouldn't take it to heart if i were yous'

I think that the main drawback in Windows security is Microsoft themselves. They can be (sort of) forgiven for releasing buggy insecure software - some of the holes had to be specifically looked for and would not be seen unless the software was in the wild. The main problem is that they are a monolithic company and would prefer not to publicise these problems until they have a fix for them. In the meantime of course, we the users are at risk.

Linuxes great strength is peer review. If you release a distro or program, within days it will have been taken apart and put back together again and any holes will be known about. Normally the fix comes in the same notification as the problem.

If MS would allow peer review and would show that they would turn their fixes around as quickly as those in Linux, their standing would increase and, even more, the community's confidence in them would multiply.

Probably not in my lifetime though!