Stores Online Question

My friend wants to start a business online and needs a shopping cart integrated.

Im going to be doing basically all the coding, graphics, ect… I can do 95% of it, or at least have the resources to do it…

Only question I have is buying things. How can I do the credit card thing? Do I have to run through a merchant account through say PayPal or Authorize.Net? Im just confused on this, and typical Google search is just… :sad:

Anyone who can point me in the right direction and such would be a major help =] Much appreciated!

(I hate credit cards… even mine.)