Ok. I will try to explain a little more about my project.
I want to control both color and brightness of 20 RGB LED-strips. Each strip contains 45 RGB LEDs, in total 20 strips times 45 LEDs = 900 LEDs. Each strip is rated 9.8W, in total 196W.
I´m using the Duemilanove board and has so far connected three seperate LEDs, one red, one green, and one blue, to three PWM pins set for output, just to learn.
I´m assuming that it will be possible to use the board with some kind of amplifier to drive the strips... but I don´t know how. Is it possible? To amplify the PWM-output?
The strips should be driven by 12VDC, 16,3A?? I´m really at the bounds of my skills here.
Next step in the plan will be to send, via wifi, input data from a Iphone-app to the Arduino, regarding brightness and color.