Kitesurfing will condition you over time all by itself. Still, early on while you are still learning it is easier to have things go wrong that may require sudden extra strength and/or endurance under load. If you pick milder conditions and go in short sessions as you get on your game this will help to reduce these factors. Stretching prior to sessions and after can go a long way to avoiding strains and injury. ChiroJoe has written a good guide to warmup stretching for kiting. It is available at kiteshops and at:
http://www.xsportshop.com/store/inde...d&productId=11
If you are looking for a conditioning workout for kiteboarding, I would think a combination of cardio and lighter weights with higher reps would be appropriate along with a thorough warmup and warm down. Focus on core strengthening activities, particularly the legs, abdominal area, and rowing related weight routines.