Using 12VDC spotlight charger on LED's?

I have an old rechargable spotlight that I never use, so I figured I would use it for parts.  Could I use the charger 120VAC/12VDC to power some LED's, like if I wanted to make an under the counter light?
If so, would it be better to run the LEDs parallel or in series?  I was reading an instructable on beginning LED's and saw that series will divide the 12 volts to each LED (4 LEDs at 3 volts each), and running parallel will send the entire 12 volts to each LED.  Would I use resistors even if I ran the LED's in a series?    If I ran the LED'S parallel, would the follow crude schematic be correct? 

Picture of Using 12VDC spotlight charger on LED's?
You can't run them in parallel.

Its not good to run them without a resistor, or some current control. Better have three LEDS in each string, with a 150 Ohm resistor on the string.  You can have lots of strings.