upgrade everything. but take it slow. one part at a time. get rid of that deraileur first though. upgrade to sram x7 or x9, or even just a better shimano. stock kona pedals arent always great. but wait till they break to get new ones. umm, really i could name a few other things, but that would depend on what type of riding your going to be doing.
if your gonna upgrade the fork get a arglye. its lighter, stiffer, and cheaper. single speed it and get some new brakes like something avid makes(juicy 3,5,7).