Terry Tao wrote on this subject; I think you will be happy with his conclusions: http://terrytao.wordpress.com/career-advice/does-one-have-to-be-a-genius-to-do-maths/
An excerpt: "The number of interesting mathematical research areas and problems to work on is vast – far more than can be covered in detail just by the “best” mathematicians, and sometimes the set of tools or ideas that you have will find something that other good mathematicians have overlooked, especially given that even the greatest mathematicians still have weaknesses in some aspects of mathematical research. As long as you have education, interest, and a reasonable amount of talent, there will be some part of mathematics where you can make a solid and useful contribution."
