watch those CFLs, they actually can make a decent amount of heat... and you gotta keep them close... theres a certain large chain home improvement store (its not home depot, they only have mercury lights) that sells 70watt MH and 150watt HPS security lights.... if you dont feel like rewiring the ballast and removing everything from the enclosure, you could just wire a plug on it and hook it up to a timer... one of these will run pretty cool, although they are kinda bulky and heavy...
i removed the photoeye, and made remote ballasts for mine... i use 2 of the MH and one HPS for my mother/clone closet, and i must say, temps arent even a worry for me (the ballasts are remoted to the ceiling of the closet)...
the 70wMH is about $70, and you can find better prices online, but you wouldnt be able to pay cash that way....