When I bought a Quicktime Pro key, I was automatically upgraded to 7.4 from 7.2 against my will.  I want to revert to 7.3 or 7.3.1, but when I try to install one of those versions I am prevented from doing so because "You cannot install Quicktime on this volume. A newer version of this software is already installed." I tried AppZap, but still got the same error message, so I put everything back where it belonged.

This came up because I want to upgrade from Media Composer v.2.8.0 to v.2.8.3 and at the same time upgrade to Quicktime 7.3 the latest supported version.  Is there a way to downgrade Quicktime without messing up my Mac (Quad 2.3 GHz G5)? 

Richard