internet explorer

I had IE7 Beta for a month. 3 days ago I downloaded the full version and installed it after uninstalling the beta. Now I have nothing, not even IE6, and I cannot install IE6 or IE7 because IE7 is half installed. Praise the Lord for Firefox! I would like to installe IE6 again after uninstalling IE7 manually. Can anyone help with this – Program files I can cope with, but which dlls and registry settings should I remove?