Controlling LED display...

I am looking for an automatic motion-sensing switch for LED display(s) that is soft-on and soft-off. That is, I want the lighting to increase in intensity when activated and then dim before turning off completely.
Can anyone suggest such a switch setup that is off-the-shelf or build me such a switch? I am pretty lame with electronic knowledge. I am an artist and need to control the LED lighting in a piece I am installing. Thanks, The Manatee :o

Fading a light on and off is a software thing. Start with the Example "Fade" and go from there:

If you don't want to do your own work, post in the Gigs and Collaborations sub-forum. Be ready to pay through the nose however.