So then you switch to another OS again. And the cycle continues... 
But seriously, everyone always says that if Linux had Windows's marketshare, it would have lots of viruses. But that idea misses something - how about nothing has such a marketshare? I'm really interested in knowing what the threat would be in Windows, Linux, and Mac OS were each given a third.
This is just the opinion of a "Microsoft shill", but...
I think all three would have malware problems, but they wouldn't all be equal. For example, right now, if WinXP/Linux/MacOSX all had 33.333% marketshare, Windows would have worse problems because they all run as admin users. Linux and Mac users would still get their boxes rooted sometimes - but only the real dumb ones who type in their admin/root password when the malware asks for it would have it happen to them.
The Linux security spokesperson would place blame the users and say they should have been running firefox chrooted/sandboxed (after all it only takes a forty minutes to set up using the fifty-two page HOTO at the linux doc project wensite) while visiting sites like butt.crack.ru.
The Apple security spokesperson would tell the Apple users that the malware problems they were experiencing really didn't exist, but if they were still concerned about security they could upgrade to the upcoming OSX 10.1.3.5.1 "Antelope" for only $199 which includes "thousands of extra security featues".
The Windows security spokesperson would remind it's users of it's "continued focus on the security of is products" and to advise all users that while they are waiting for the scheduled patch in 26 days, they could visit and follow the simple thirty-seven step workaround found in KB article "KB7621375122422" at Microsoft.com.
The only precedent we have as far as a non MS desktop OS being afected by viruses was Apple back when they still had a 15% marketrshare. If 15% markethshare is enough, then I would think 33% would be more than plenty.
