If you're into building things like this you might want to check out TI's line of LED drivers: http://focus.ti.com/paramsearch/docs...ODE_STRY_PGE_T
National also has a great section on LED power:http://www.national.com/analog/led/high_brightness
Maxim has a bunch of really cool led drivers as well, but I've found them to be a little on the expensive side: http://www.maxim-ic.com/products/display/

Mike Tripoli