cooling idea's

I have a 1000w light in a closet that is 41/2x21/2x8 feet, and I know that I am going to have some problems with heat, so I am looking for some suggestions on how I can cool off my closet. I am thinking of putting a bathroom fan in the wall beside the light and venting it through my roof with a whirly bird.

It all depends on you intake. You can vent like you say just put a filter or can fan or something to stop smell from getting out. GREAT WAY TO BE DETECTED. You can cut a hole and have a passive intake and test it. If it is not doing the trick add one of those bathroom fans outside into your room. One last thing if you are exhausting you'll need a more appropriate fan designed for the power to exhaust the room faster. good luck

would there be enough room in the closet for one. I don't know how big they are.

Portable A/c is a big no-no for growing. They use a small amount of air from the room to vent over the hot side of the A/C and then it goes out a window. There are a VERY few portable A/C's that have 2 hoses on the back. This what you want, if it only has 1 hose then no-no.

what about an ice cooled fan hung blowing on the bulb. My ballast is kept out side the closet aswell.