Thanks!, i was reading about constant current drivers (i didn't knew much about them)...
It's seems that i'll have to do something like this:http://www.reuk.co.uk/Using-The-LM317T-With-LED-Lighting.htm
Is it correct to ditch the 7805 for a LM317T and a resistor?
(of course i'm considering to use a couple of this and a heatsink...)
Now.. How would this solution work with the TIP122 Transistor connected between the current regulator and the leds?
Also this means I don't have to connect series resistor with the leds, given that the current is already regulated?