Hi, I'm new to programing and I need help with programming the arduino diecimila to control a servo. I I want to do is make the servo shaft spin. please help. 
i used the sweep example and i can feel vibrations when i hold it in my hand, but the shaft does not spin, i tried this on both motors, the first time it worked but hasn't since then.
Double check the wiring. Also check that the servo has enough power. The first servo I tried to run on my arduino (a low cost standard size hobby servo) worked intermitantly because it required more power than the arduino could provide. Using a separate power source for the servo (with a common ground) solved that problem for me.
Good luck!
Using seperate power supplies for servos (due to electrical noise and consumption) is recommended: !As long as they have a common ground!
And make sure to use a good resistor on the signal connection...