Checkout Button

I want to replace the chekcout button on the view cart page.

I tried to edit the checkout.tpl in: skins/my_skin/customer/buttons/checkout.tpl

But I couldn’t find the image to replace in that file. Am I looking in the wrong place or is there some other way of doing it.

Also I am using a merchant account and google checkout. I wanted to put a “OR” in between the two checkout buttons like they did here:

Any way of doing that?

Thanks for your help. I really appreciate it.