<p>I'm using PayPal Website Payments Standard.  Whenever the user lands on PayPal with the variables I sent, it shows a PayPal Login form and at the bottom it shows "Don't have a PayPal account? Use your credit card or bank account (where available)."</p>

<p>I want it to default to always ask for credit card and maybe say "Have PayPal?  Use that!".  Any ideas?</p>

On
a thread in the PayPal Developer Community
they explain it with cookies based visits to the checkout page.
Basically if PayPal detects you being a user and spots their cookie, they will show the login form by default.
If they can't see that cookie, then they will show the credit card option first with a note that if you already have a PayPal account, to log in.
So the answer is no.