I bought the Porter Cable Orbital Polisher and thought it did a great job on my car. Following Atomic 80's wonderful thread, I taped up all the cracks and plastic on my car and wend with polish, glaze, and wax.
The results were fantastic. The machine really made a huge difference - no way I could have done that polish job by hand. As to the comment about not using machines - I'm no expert, but I would think that it's the products you apply, not the machine, that could cause harm. I went with a very mild polish (Menzerna Final Polish II).
I bought everything at properautocare.com. They are very helpful - feels like a family run operation from the nature of their helpful responses.
Definitely check out Atomic 80's thread. It's worth the read.
Pete