Is it possible to get into a top Grad school without an internship or research?

I am a sopre in college. Majoring in math and economics. In grad school I want to study either financial mathematics (or financial engineering) or get a phd in math (pure math...not financial). I was wondering how hard it is to get into a TOP SCHOOL without research experience or an internship in college. I want to graduate in spring 2011....if i use my summer in 2010 to do an internship it will probably make me miss out on some math cles (i would still have the bare minimum to apply for a phd math but i wont be a double major...only economics). My question is....if I use summer 2010 to take advanced math cles instead of an internship...how badly will that affect my application for graduate school. I intend to apply to Columbia, UCLA, Princeton, NYU, Baruch, Carnegie mellon.