PWM... hmmm why didn't I think of that earlier! But then you will need a refresh rate WAY much more than 100hz, say 1Khz?

Thanks for the tip Erik and Michael, I'll get google running :)

BTW Erik, you say ledpanels are your businness. Are there any good books available on this matter? And what about the hardware, I can buy red, green and yellow leds for about 0.10$/piece (±70mcd) true rgb ones are at least about 2.5$!!!!!!! Sure makes a panel REALLY expensive! Or are assembled boards cheaper? any hints on where to buy them? (preferrably in europe, I live in Belgium)

thanks again for the posts!