Hey Jut -
It looks like you are local to PDX? I have a gallon of Auto Magic Hard Water Spot Remover. It works very well. If you want to bring a spray bottle by my house, I would fill you up and you can try it. As Zack said above, it depends on how deep your water spots are. I have heard good thing about his products, but if you want to try this first, feel free to hit me up.
Either way you are going to have to put in some elbow grease. Next step would be to get some compound and polish her down if you know what you are doing with a buffer.
After you get it all cleaned up, give it a good coat of wax and as long as you wipe it down good after each use, you should be good to go.