This is copied from my post on ZDNet
Well considering how much effort Microsoft has put into the Windows Genuine Advantage program. It's suprising to learn they are going to disable it in Internet Explorer 7 for users on XP.
But since launch IE7 hasn't really seen a big uptake. people choosing to remain on IE6 either by choice or because they can't pass the WGA validation. Another reason is that people are using other browsers now and like some of the options other browser offer.
Personally I have IE7 on my desktop and still have IE6 on my laptop, but always I use Firefox on both, unless i'm website testing. 🙂
Source : IE Blog