How to Install Quake 4 1.3
 
OK 1.3 is not 1.4..
1.3 plays just like 1.0 but with added maps and some new sounds when you get hit or die.
Find your quake 4 1.0 in your PC and copy it and rename the one you have 1.3 and paste the one you copied next to it.. ( so now you'll have two 1.3 and quake 4 1.0)
or
Find your quake 4 1.0 in your PC and copy and paste it into a new folder you will make next to the original ( rename new folder 1.3)
download patch 1.3 from    www.quakeunity.com/file=2327 or from my site 1.3
and run it to your newly created quake 4 1.3 
now you have 1.0 and 1.3.. your done!!
Play and have fun with the new maps.