I've found the best way for me to power the high power LEDs (you know the ones that come on a star metal base) is with a LED Driver chip like the ZXLD1350 or ZXLD1362. There are other similar types of this chip and other manufacturers they hold a constant current on the LED and you can put several high powered LEDs in series with one of these drivers. I made some High Power LED Driver Boards today with the ZXLD1362, my board can run up to five 1W or 3W LEDs depending on how the sensing resistors are setup,
Check out this Youtube Video with schematic and subscribe to my youtube chammel for uodsted on PCB etching, drilling, exposure, etc...
Youtube Video...
http://youtu.be/IRFffWl1g28Have Fun,,,, Tom