You CAN switch from PayPal to credit card payments.
You will need to create a new account using a different email address than your existing account. For more information on creating a new account, please take a look at this video tutorial. We will be able to migrate your websites over to your new account, so there's no need to add any sites. All of your backups will remain intact.
Once you have created the new account, contact support. Let us know the email address of your old account and the new one, and we will move all your sites, databases and backups over for you.
The system takes a few hours to purge the old account from our system, so after a little while, you can change your email address back to the old email address if you wish.