Many of our clients use IE as their browser of choice, as do many of their site visitors. We've noted in the past that the Drupal admin interface is optimized for Firefox, that is certain admin features work better in Firefox than IE. Another major incentive to switch browsers came out today.
Mashable is reporting a major new security exploit affecting IE7, 8 and 9 on computers running Windows XP, Vista and 7. Microsoft has not yet released a security update for the exploit. We strongly encourage our clients to switch to a different browser if not permanently then at least until this issue is resolved.