I would start off with a medium grade pad and product. So this would be a medium cut pad from any reputable company like Lake Country, Meguiars, etc. For a PC you need a product designed for it like Meguiars #83 DACP. First wash the car to get rid of any dirt, clay it quickly to get rid of any embedded grit that may cause swirls and then go to town with the PC, medium cut pad and #83. Work real slow, small area at a time and use a decent amount of pressure and plenty of product. Try this first and see if that does the trick. If you need more cut, first switch with a higher cut foam pad OR just do it again, sometimes it takes multiple applications to get the results you want.
What you may want to do, is go to MeguiarsOnline.com, register and look at their 2008 detailing class calendar. I think they have a class in late January in the O.C. that's open to registered members. It's a totally free class, free lunch, free goody bag. They teach you to work the PC bufffer, and different products. If your car is that bad, they may make it the class project. Wash the car before you get there so you can start polishing. All their products are there for you to use for free while you are there.