Internet Explorer 7 has tabbed browsing ala Firefox, and a host of new features. Microsoft announced recently that this new IE will be deployed via auto-updates:
http://blogs.msdn.com/ie/archive/2006/07/26/678149.aspx
If you need to control user updates for legacy apps/sites not tested on IE 7 yet or for other mgmt. reasons, there is a blocker kit for the update as well:
http://www.microsoft.com/downloads/details.aspx?FamilyId=4516A6F7-5D44-482B-9DBD-869B4A90159C&displaylang=en
Enjoy good network health,
Port80