Considering going HPS

my grow box is 12wx18lx30h
right now i have 5 cfls all around 25 watts some bright white some daylight
i think i need more light but i'm worried that an hps will get too hot or not even be able to fit in my box
i'm only growing 1 or 2 plants at a time in the box (bag seeds now, ordering lowryders this week)
my temps get up to like 80 now tops
so can i even do an hps in here or should i just get alot more cfls?
also if i do get an hps how can i keep the temp down?
thanks guys

I think you will be ok. I have cfls too, but u should have enough height to keep it away from the plants. You may have to lst more to keep it shorter cause the light will have to be further away than the cfls.

What wattage do i need
any recommendations for ballasts and bulbs and whatnot

150watt HPS will work fine in there. Or you could get two 70watt HPS's (i like the latter, spread the light around a little more)

I just set up a small closet (18x20)using a 150 watt HPS simular to this but 1/2 the price.
http://www.lowes.com/pd_102355-337-HPFZ15C
I removed the ballast to put above the closet & drilled 6 3/4 holes on 1 side & a 2 inch hole on the other & added a piece of 2 in pvc pipe to duct outside the closet w/ a PC fan.temps only go up a degree or 2 after running overnight.
a local hardware store sells replacement globes for a huricane lamp,I remoted the bulb & used 1 as a cooltube again w/ pvc pipe & a pc fan & had the same results so you should be fine w/ a little ingenuity.