Thanks Dennis. I'm assuming (from reading some of your other posts) that you are one of the Sonic Foundry team and speaking from a position of knowledge. I'm going to also assume that it should be OK to delete CDA 4.0 from my drive and its absence won't alter the performance of CDA 5.0. Thanks again.
You probably already know this but make sure you do an "Uninstall". Just deleting folders could cause problems as Sonic Foundry puts a few folders in the program files folder.
If you uninstall, some folders may still remain but do not hinder anything but a little space.