I have one from my pre-autopian days, and I haven't touched it in quite a while. I actually stopped using it before I found this place because I wasn't happy with the results I got from it. I switched to the PC because of:
1. Extra power
2. Removeable (and therefore washable and interchangeable) pads
2. Smaller size (more maneuverable and easier to hold)
I was never able to use the cheap orbital for polishing, and I'm not sure what bonnet you would use to attempt that. I never wanted to use anything on the bare foam pad that comes attached to it because it's fairly stiff and I think therefore fairly aggressive, and I never knew how to clean it. I did use it for applying liquid waxes (Meg's GC) using the little bonnets that you can get for applying wax. That just made a big mess of everything. I did use the terry bonnets to remove wax residue. I think I put swirls in with those terry bonnets.... they're not the softest things in the world.
I can't say that I was happy at all with my cheap sears orbital... I never got much good use out of it. However, I absolutely love my PC. I can do things to my paint that I could never do before, and my car looks better than in years (it was not cared for well for quite a while).
John