Google doesn't like Microsoft and that's no secret.

So with the new year Google's planning to phase out support for IE 6.0. The Internet has evolved tremendously and old browsers like IE 6 do not support a number of new features like interactive applications, that include voice and video. To ensure that users get the complete benefit of web apps Google's urging web users to update their browsers as soon as possible.

Google suggests:

Microsoft Internet Explorer 7.0+,
Mozilla Firefox 3.0+
Google Chrome 4.0+
Safari 3.0+

Google's beginning to phase out their support, starting with Google Docs and Google Sites. From March 1 key functionalities within these products – as well as new Docs and Sites features — won’t work properly in older browsers.