That so many Windows users see value in, and frequent, a site that is definitely pro-linux/bsd/open source, and what is arguably, even with all the "web 2.0" junk, the most influential tech forum on the net, says that Ballmer is right when Microsoft tells the SEC that linux and open source are the biggest threat to Microsoft.
Think about it - even with less than 1% of the desktop, and being distributed for free, it's more of a threat than Apple, who are worth more than Microsoft.
I don't call them poseur wannabes - I call them fresh blood :-)
Actually, I'm a Windows user, I've been coming to Slashdot for years, and I'm not interested in open source, linux, or BSD, and probably never will be, because they don't offer me anything I want that I don't already have with Windows. As a gamer, Windows gives me everything I need - certainly much more than an open source OS.
I come for the tech articles and news posts. I would wager that this is true of the general Slashdot population. That's not to say that the number of folks interested in open source isn't higher here than in the general population, as a large number of the articles deal with open source topics.