Actually, I went over to Verisign
and one of those "annoying" chat boxes popped up asking me if I needed any help. The guy I talked to was very helpful and explained everything to me. I can't really remember everything he said right now, but he sent me an e-mail were I could try a non-functional demo of the credit card processing system. I haven't used it (the health club thing hasn't worked out yet), but I learned a lot from what he told me.
As I recall, it costs about $500 to get set up with a merchant account. Paypal doesn't have an up-front cost like that, but the paypal fee would catch up with you after you've made about $20,000.
As much as I used to hate those chat boxes, that one saved me a lot of time.