Google docs will no longer support Internet Explorer 6 and other older browsers. On march 1, 2010 these older browsers will start working either very slow or will not work at all with google docs.
This step has been taken in favor of new high speed docs site with newer standards like HTML 5.
The site will continue to work on Internet Explorer 7 and above, Fire Fox 3 and above, Chrome 3 and above and safari 3 and above.
Google also plans to phase out these older browsers from Google Mail and Google Calendar as well later in 2010.