This questionis a follow on to this question.
I forgot to mention; we want the customer to be able to pay either through paypal (with paypal account) or via credit card. Does the awarded answer, based on http://www.evoluted.net/thinktank/web-development/paypal-php-integration
cover that case as well? Also, in some cases there may be a buyer whose paypal email is not the same as that we have in our database for that client; I presume the payer email used must be that of the payers paypal account, assuming the buyer want's to use their paypal account.