Communication with another arduino

I am planning on recreating the jeeputer with some added security and some features and what I wanna do is have the arduino which is connected to the keypad be shortcuts after it is started up (press 1 to turn off and on radio press 2 turn cb on and off and so on) this way I dont have to scroll through pages while driving. but I am not entirely sure on how to have it send the commands to the other arduino. Can someone explain on how to do this or point me to a tutorial on how to do this.

http://www.google.com/search?q=connect+arduinos

just connect the rx to tx and tx to rx.

Tangent to the OP, how hard is it to get two arduinos running together via SPI? Anyone have a good example? I’m really misreble without something to reference.