Need help getting checkout button flush with otherbuttons.

My problem can be seen here (http://mermapillar.com/shop_thermals.php). I need
to get the button that says "Checkout" to rest flush with the other buttons in
the bar ("bibs", "thermals", etc.) When I add the form code from PayPal around
the "checkout" button image, the shift occurs.

My end goal is to have the round shopping cart graphic and the "checkout" text
button both have the same function. Also, I would like to add the rollover
functionality to the "checkout" button like the other buttons in the row.

Any help is appreciated.