Simple electronics help

[Ghoulish Delight]

I have a small toy traffic light. Right now it's lit by 3 night-light sized blinker bulbs in series, one for each color. I'd like to modify it to actually mimic traffic light timing, rather than just the slow random blinking.

I figure an Arduino is the way to go. Programming the logic would be a no brainer, but I'm very very very unknowledgable when it comes to the wiring/resistering side of things. I've tried Googling for info, but everything is either too simple (i.e., sticking 3 tiny LEDs on a breadboard) or too complex (getting hold of a full size traffic light with all the parts and bits). I can't find anything for this in-between project.

Anyone have the kind of knowledge necessary to walk me through what I'd need to get an Arduino (probably a Duemilanove 328) to independently control 3 night lights (4watt/120v - or possibly 1watt/120v LED variety)?