I'm not a techie, but as someone who's been using Windows since its first incarnation in Aldus Pagemaker, I thought I'd never stray from MS.
After his past year of almost daily security warnings, holes, updates, etc., I've spent megabucks on security programs, and have spent countless wasted hours scanning for spyware, trojans, worms, et al, with the constant worry that the computers I use to run our business would be compromised.
I'm typing this from Firefox on a Xandros Linux (which was designed for the non-techie) -- and no, Linux won't run all those Windows programs I need to conduct business, but it will keep me saner and safer as my main internet interface.
Of course, it can be argued that MS has all those security holes because it is one hugely distributed target, whereas Linux and Apple aren't worth the trouble for hackers, but for now, I'd rather spend more time on keeping my business going than worrying about the next security picadillo, and the best way to insure that with minimal efforts is to keep the XP boxes offline.
My (rather longwinded) point is that if MS doesn't pay attention to the Firefox trend, they will miss the signs that the little guy is not only tired of IE's holes, they are also tired of fending off attacks on Windows itself. XP is awesome, but taking it on the internet is now like going into battle with a thousand pounds of armor that may or may not protect you.