Its always best to ask if you arent sure.
First, you want to make a backup of your current versions "include" and "lib" folders..
by default they are at :
C:\Program Files\The Game Creators\DarkGDK\include
and
C:\Program Files\The Game Creators\DarkGDK\lib\vs9
once you have made your backup, simply extract the 7.3 archive into the DarkGDK directory, allowing it to overwrite the existing files.
You should end up with a folder structure that is exactly the same, except for the addition of a "vs9debug" folder inside the "lib" folder, alonside "vs9"
After you have extracted the archive, you should be able to just compile your programs as normal, if not, then you can always restore from the backup that you made(you did make one?
)
If it ain't broke.... DONT FIX IT !!!