need help setting up my grow cabinet

I'm kinda new to growing,I'm on my 2nd grow.first grow was a bust.made some mistakes that I've corrected this time around but I have a new plan.currently I'm growing 2 unknown bagseed plants in an exoterra reptile terrarium that I have lined with mylar and fixed 2 68 watt and 2 55 watt cfl bulbs for flowering.my next project is going to be a sterilite 2 shelf cabinet from Walmart.it measures 35 3/4" tall 25 3/4" wide and 19" deep.my plans are to take out the shelves so that its all open and mount a 400w cooltube from the top with mh during veg and hps during flower.along with some computer fans mounted at the top on each side of the tube one pushing one pulling air through the tube and 2 more in the plant zone .my main question is how hot will a 400 watt light make a space that size and will the 2 computer fans be enough to keep it cool.my current box measures 12x12 and 18" tall.with one small fan blowing in the door and one computer fan mounted I'm my homemade reflector hood pushing the heat from the cfl out it stays right around 76°f.any help would be great.I plan on buying and starting the cabinet pretty soon after I harvest what I have going now.thanks

Was also concidering putting a carbon filter and inline fan in place of the computer fans for pulling air from inside the cabinet through the cooltube and out of the cabinet.

Computer fans will not be big enough a 400watt will warm that area farely quickly. Yku need to up you fan 200 cfm w a carbon filter for flower. Once in flower connect filter to light and then to fan and that will keep negative pressure in tent keep your light cool and smell controlled in 1 setuo the fan is a touch big but better to replenish the air faster then not fast enough. Buy a small desk fan like 6 inch or so and that should plenty of air movement.

I have a 6" desk fan hanging on my current box feeding air in.what about mounting the fan on the outside of the cabinet so that way only the filter will take up inside space.

I may just scratch the plan.I wanted to keep the cabinet kinda stealth and putting a big fan on it will probably make more noise than what I want.

Why don't you search the forum for someone doing well with LEDs. They don't make very much heat. Sorry I don't have an example, but LED grow is better than no grow.

Thanks,I kinda forgot about led,ice looked at some and thought about it as an option then set my mind to going mh/hps but I may look into finding a led setup to fit in.I've been trying to not spend much on what I've got growing now but CFLs just aren't doing it for me.