Currently, when text, java, python, perl, etc. files are doubled clicked gedit opens. Anyone know how to make kate the default editor? Thanks.

If you are using KDE, you will need to alter the appropriate File Assocations in System Settings > Advanced > File Assocations.

You can use the command "file --mime-type <file>" to determine what mime type your various files are in order to change the needed associations.

You can do it within specific apps as well; Konqueror has it's own file associations dialog.

The fact that you have gedit as the default indicates that you probably have Gnome installed. Is that the environment you are running? If so you have to look for Gnome's file associations (which may be tucked away in a corner of gconf or something). Otherwise it may depend on which file manager you are using to locate the files (e.g. dolphin, konqueror, nautilus, thunar, etc.), and you will need to do some digging around that filemover's settings and documentation to see where that is configured.