Changing wording for check or money order

My client would like to only accept money orders and not checks. The confirmation screen applies "You can now send us a check for the amount of $....." I've looked all over in the payment plugin info and not found a way to change 'check' to 'money order'. Is there a file that produces this?

Thanks, Nicolas! That was easy enough. One more thing... The icon by default says 'check'. Where can I put a new icon that says 'money order' so that it may be selectable?

Thanks!