Not sure if this helps but, if you go to Favourites and scroll to the bottom do you get an entry titled "Microsoft"? click on this and half way down you should see, "IE on Microsoft", clicking on this leads to:
http://www.microsoft.com/windows/ie/default.mspx and again half way down left side you will see "IE6" not sure if this will take you to your original IE6 installation or just give you the opportunity to download it again.
Been using IE7 for a while now, ZoneAlarm Pro and Norton Ant-Virus, (but NOT the complete Norton Security System) and so far, so good, also have Microsofts own security system working, it would seem, compatibly!