Player 4.05 is the latest release of the version 4 software so it would be the recommended file to use.
As far as I know you cannot install multiple versions of Player onto one computer.
By default the Player installs into a single folder in "\Program Files (x86)\VMware\VMware Player", so installing a different version would overwrite the files in this folder and totally mess up Player. See the link kb.vmware.com/kb/1003897
So you would have to install Player 4.05 onto a different computer from the one that Player 5 is installed onto.