Nah, don't put any fans in. Just put the lights at the bottom and run a couple big dryer hose air pipes from the top of the cupboard down back down to the bottom. Then convection will move the air around.
Hehe, Ok, fans would probably be more tidy. Don't use computer fans. Just get a small desk fan from the warehouse. More power, probably quieter, a lot cheaper and doesn't need a 12V transformer.