high man, rather than reiterate what's already been said, here's some links i
think might help you more than i can, hell, i know they will help you if you go
exploring, lol.

anyway, the first is a thread by redgreenery explaining air-flow, i think you'll
find much there that will help.

the second is to an awesome box built by Yukon, an NGB style box and
again, i think you'll learn much.

the last is to a collection of DIY projects that are all very good.

oh yeah, if you go to a discount builders supply, you can get fixtures
like this for very little money.

and i'd also suggest you switch to lower wattage bulbs, i use 23's and 26's,
they are easier to find, give you more points of light and they are
cheap,
usually 3, sometimes 4, for $6.99, a much better value than the
42's and even the 30's.

Ventilation 101 (redgreenry)

Yukon's awesome box

DIY~ LINK-O-RAMA