Linear Voltage Regulators make a regulated LOWER voltage out of an unregulated HIGHER voltage. You are looking for a step-up (Boost) Switching Power Supply.
www.national.com and click on the "Power" tab in the WEBENCH Designer area on the right side of the page. It'll give you a dozen or two things to chose from. However, and MikeMI pointed out it won't be as simple as something like a 7805.