You prob want a cabinet similersomething like this.

http://www.rittal.com/uk-en/product/...ductID=PRO0023

Most proffesional cnc machines will have a fan to cool with a filter to stop the majourity of crap getting inside. I guess you might have some long running times so you might want to add some sort of fan on your stepper drivers or at least bolt them to a heatsink or something. If you really want to push the boat out you could bolt them to a hunk of aluminium and water cool the block. My thermwood machine has a airconditioning unit attached to cool the insides of the cabinet.