Paypal won't let me use my Credit Card

Yes, you can probably use a credit card with Paypal even if you have a Paypal account.  Paypal does not like when you do this, so they make it a little tricky.  But we've figured out the tricks for you.

In the first Paypal page, do not "LOG IN TO PAYPAL".  Instead, click "Use your credit card...Continue".

PaypalCreditCard1

In case they didn't trick you the first time, they try again on the second page.  Again, do not "Log In".  Instead, fill in your payment information.  For highest probability of success, use a credit card that is not listed in your Paypal account, if you have one…

PaypalCreditCard2

I have been told that if the credit card you enter is listed in your Paypal account, Paypal will reject it and tell you to use your Paypal account.  However, I tested this case on 2009 Jan 18, and my Paypal-registered MasterCard was not rejected.  I suppose Paypal's policies on this matter could change at any time.  If you are rejected, you might want to retry with a different credit card if you have one, or maybe try a different telephone number or email address.

If all this fails, the only solutions are to either go back and select Google Checkout instead, or else enter an order via email and pay by mail.

For future reference, remember two words to pay your way with Paypal: Keep Left.