I thought I had read that you already ordered a 400w HPS light? If you use a cool tube ($60) it will have minimal heat - maybe raise the temps 5 degrees. Youll need the tube and a fan to move the air through it.

I gave up on CFLs for the same reason - in the wattages needed to get good light, they DO produce heat contrary to what everyone says. If I am gonna combat heat problems, at least I want good light from it.