If you prefer to use your credit card for payment, and not sign up for a PayPal account...
After registering and entering your personal info, or after logging in (if you already have an account), scroll down to the bottom of the page and you will see:
Prefer to pay with Credit Card or Debit Card (instead of PayPal)... click this link "Pay with Credit/Debit Card" and scroll down to "Pay with Debit or Credit Card".
Click the "Pay with Credit/Debit Card" link. On the next page, scroll down and click "Pay with Debit or Credit Card". Now you can pay with your credit/debit card and you won't have to sign up for a PayPal account.
* Note - currently this option is available only for Premium Membership sign-ups, Premium Membership - Discounted sign-ups (renewals), and the Playbook download sign-ups.