Also "there is no _one_ Linux anymore" (You have Windows XP)
"...15 major releases (distros) and many of them don't work with each other.."
This is actually a good thing.
The reason why social engineering is easier in the Windows world is also an illustration of the dangers inherent in any monoculture, whether biological or technological. In the same way that genetic diversity in a population of living creatures is desirable because it reduces the likelihood that an illness - like a virus - will utterly wipe out every animal or plant, diversity in computing environments helps to protect the users of those devices.
Linux runs on many architectures, not just Intel, and there are many versions of Linux, many packaging systems, and many shells. But most obvious to the end user, Linux mail clients and address books are far from standardized. KMail, Mozilla Mail, Evolution, pine, mutt, emacs ... the list goes on. It's simply not like the Windows world, in which Microsoft's email programs - Outlook and Outlook Express - dominate. In the Windows world, a virus writer knows how the monoculture operates, so he can target his virus, secure in the knowledge that millions of systems have the same vulnerability. A virus targeted to a specific vulnerability in Evolution, on the other hand, might affect some people, but not everyone using Linux. The growth of the Microsoft monoculture in computing is a dangerous thing for users of Microsoft products, but also for all computing users, who suffer the consequences of disasters in that environment, such as wasted network resources, dangers to national security, and lost productivity
The content above is an extract from the article on this website
http://www.theregister.co.uk/2003/10/06/linux_vs_windows_viruses/
To understand the dangers of a monoculture read this document.
http://www.ccianet.org/papers/cyberinsecurity.pdf
Regards
Rishi