Hopefully you'll get the spelling correct (or fix the typo) :

We Perfer PayPal

The file you need to look at is

tpl_checkout_payment_default.php

and I trust you know that it's a good idea to create an override for this after editing.

The best way to include your message would be via a proper DEFINE, so something like:

PHP Code:
<div><?php echo TEXT_PAYPAL_PREFERRED;?></div>
... would be appropriate, where the define for that constant is in the language file checkout_payment.php, and would look like this:

PHP Code:
define('TEXT_PAYPAL_PREFERRED','We Prefer PayPal');