it all depends on your pocket book....definately need a rear skid for gncc. i tore mine up within 30 minutes in the trails. the shocks help keep the a-arms off the ground and the bottom skid is awsome for stock. the sidewalls on the stock tires are that great, but a tube and fix-a-flat works wonders.
for mx, get it wider and lower. small tires, arms, axle, and shocks if you want, but in my opinion, the stockers are great. also, for either one, you might want a pipe or take you spark arrestor out.
One that works and will never really mess up is the GYT-R one. Made for the bike. It's designed jsut like the stock one, but like 1/2 inch aluminum i think. Awsome....costly, but you get what you pay for. The downside, it doesn't cover your swingarm. The PRM covers it all, but it will bend on you quicker and isn't as strong. Cheaper too. I have the GYT-R and will try to post pics when i get a chance in the next couple of days... :lol