.mov files are container files. It is likely that the codec inside of the file is something that QT X does not understand. When QT X does not understand a file, it is suppose to load QuickTime Player 7, if available. You can install that via the OS X install DVD. It will end up in the Applications/Utilities folder.
AFAIK, you are the first to report this issue. Which version of QT 7 are you trying to install? Virtually every system that has QT 7 and QT X simultaneously installed have them installed on the same drive. Certainly there are installed on the same drive of my system.I tried to go through the quicktime website and download the qt7 installer dmg but when I go through the installation process it says it cannot install it on a drive where qtX exists, ...