If you have a card with a link to the Paypal system, to pay using the credit card option you have to log in to PayPal and disassociate the card with the account. Or go ahead and make it a Paypal transaction.
Also … for those using the Paypal “pay by checking account/Echeck option,” please understand that PayPal has a 5-10 business day float on those transactions. That means the transaction does not post to the Straight Dope side of things until the checking account draft processes. That may cause you to lose your membership if it expires before the Echeck transaction goes through. So if you’re going to use Echeck do it no less than two weeks before your subscription expires.