A hole with a CPU fan will not be enough those MH/HPS lighting systems kick out crazy heat. My best suggestion is dont rush the grow get your lights 1st then do a test run as if you had your plants in their setup for a day. Record the Temps to see how it goes. Best Temps I believe are anywere from around 70-80%F, 85 to but if you exceed those temps you need to have good ventalation with enough CO2.
2 sites for lighting systems
lights Thanks to TC for this site
another site for lights :thumbsup: