First of all, I *never* for the life of me understood why sales charts stack PC in one category, and EVERY console in another. It isn't fair at all, PS2 and Xbox is as different as PC and Xbox - hell, an Xbox is closer to a PC technically speaking. If anything, consoles are more competitors with each other than PC since plenty of people will have a game PC and console - why on earth they bunch them together is a mystery to me.
Secondly, go look at total sales. The Sims for PC has sold over 50 million copies collectively. The Sims 2, over 100m including expansion packs. Keep in mind, a lot of PC game sales also happen online now, either streamed or via online stores - neither of which typically count in sales charts. For example, Assassin's Creed PC will be available via Steam. There are over 15 million user accounts on Steam alone, and there are quite a few other digital delivery systems out there - Direct2Drive, EA has one, a few large European strategy game makers have one. Like usual, PC is just ahead of the curve. One day digital delivery will dominate consoles too.