Ventilation for this Cabinet

Here is a pick of my cabinet I am in the process of building for growth. The dimensions are:

DEPTH INCHES 20-1/4"
HEIGHT INCHES 36-3/8"
WIDTH INCHES 30-3/8"

My question is how many intake and exhaust fans should I have? I plan on using normal PC fans. Also I plan on growing 3-4 plants in this cabinet.

One more thing. Where is the best places to position the fans on the cabinet?

Put one fan at the bottom right in the back sucking outside air into the box, and one fan at the top left in the back blowing hot air out. That should work fine, as long as you don't put too big (hot) of a light in there.

Cool thanks.

Computer fans are only going to work if your using CFL's.

what light are you goin to use