need help with ventalation, and general air flow.

hey, ill be getting a 2'8" x 2'8" x 6' grow tent (i plan on growing 2 plants)
a 400w mh/hps aircooled system with a digital ballast that is dimmable
it will be a soil grow, and the tent will be in my room.
i keep hearing about how much heat the 400w will produce, so i am worried.
what do i need and how would it be set up? should i get a 150cfm Soler and Palau inline fan, and connect it to the light hood, and then lead it out the top, and then just leave some of the tent access points open to suck in air from the vacum effect? im trying to spend little money, but have a good and quiet system, and i dont want my plants to be to hot and me not have money, i havent started growing yet.

so do you have a fan to cool the hood? and you are wondering about a second fan to exhaust the room? If you don't have a fan than you will need one for the air cooled hood.....a good setup is to attach a canfan to a filter.....then to the hood.....and out the vent. This sucks air through the filter....cleans it and blows through the light. Get a fan with enough cfm to change the air 1-3 times a minute...
good luck.