What's dishonest about it?
* it appropriates as "linux" a lot of software and projects which are not part of linux and work just as well on other OSes (and in some cases windows as well). KDE and gnome and the windows managers are not linux, neither are the office applications, or games, or the networking security layers, or the security model etc.
* it totally ignores what can be achieved under windows with open source and freeware tools, when it talks about "free games" or "customise your desktop" or the applications available
(to be fair he does address most of these 2 points in his faq for geeks
http://www.whylinuxisbetter.net/faq.php but he still fails to mention the other free oses)
I have used linux and bsd and other unices and windows and os/2 etc. I'm all for linux getting more popular, but i think it will happen simply as people won't want to keep upgrading all the time, will think about green etc. But one things that bothers me is the linux community always implying that all the open source and gnu etc. software is part of "linux". It is a dishonest appropriation of other peoples work, and because linux got a lot of press a lot of people actually believe that things like gimp, apache or gnome are "linux".
1. viruses and 3. security
Will probably start becoming a problem as more "mainstream" people move to linux and probably log in as root all the time. Plenty of worms and rootkits out there waiting to ambush the less sophisticated, and there have been a lot of high profile security flows in the open source products recently. They get fixed faster, of course, and they get found faster, but they do happen.
2. stability
I should agree with that but actually stability is typically down to what the user does with their machine. Install a load of crap and you get an unstable machine. I have seen windowsNT servers that had stayed up forever and I have had redhat servers that just would crash once a month, no matter what we tried (it seemed to be the networking layers, possibly driver...). But in my experience the most stable OSes I ever worked with were BSD and Solaris.
6. why should you need to install more stuff
Well that is one i strongly disagree on. I always do a minimal install of linux and then install just what i need. All the crap that is installed by default for convenience is a security risk for me. And it uses up disk space and resources too
the "international" point
What can I say, that's just the microsoft is the evil american corporation argument. So are the people who make your computer hardware, or car, or breakfast cereal, or clothing, or microwave oven...
A point like that really weakens the whole argument on this page