When in doubt, blame Microsoft. While I'm not the biggest fan of Microsoft, you cannot simply blame all worms and virii on them. You can't just simply say that it's their fault - that their code is faulty. True, there are flaws in the system. Not everything is 100% secure. If the blame doesn't lie on Microsoft, where does it lie? The blame lies with the end-user. The blame lies with the idiot who doesn't patch his machine. The blame lies with the tech un-savvy who doesn't use a firewall on a broadband connection. The blame does not lie with Microsoft.

So, it's not Microsoft's fault, but rather the user. But, to play the devil's advocate, you ask, "why is it only Windows machines that have worms and virii?" Is it because they are poorly coded? No. Is it because of stupid users? Partly. Is it because worms and virii only target Windows machines because they're used by 95%* of the population? Exactly. Why the hell would you make a worm that affects only 1% of the computers on the 'net? That just makes no sense. If you want to cause havoc, steal passwords, whatever your intentions, you go after the largest target base. It's really that simple.

*95% made up. Might be more, might be less, but I'm sure the majority of the population uses Microsoft Windows.

URL: Why I Hate Microsoft - Part 1: Worms and Viruses