GraduateSchoolNut's concern is right. The amount is non-refundable, I am ready to pay if funding is available but... Moreover it is my first letter of acceptance, yet to hear from any other school, and yes I applied to Electrical Engineering PhD for Fall 2009. I applied to UCR, UTK, Notre Dame and South Carolina other than Drexel.
But what if no professor replies (regarding funds) within April 15 and....? Can't imagine.
And in case of drexel, even some professor's page has very few amount of information about their research interest, in some cases Lab's webpage is unavailable though link i