Yep, IE 5... thanks for the heads up. I only use font smoothing for fonts 14 points and up. That way you get the smoothed effect when you need it, without hurting general performance (since 12-point is used everywhere).
Of course, ever since IE 5 CNN's page displays 14 point fonts (even though my default is 12 point) and just looks crappy all around, but what can you do... it is the best all-purpose browser.