hid lighting gives off way more heat than floros/cfls
a good rule of thumb is 50 watts per square foot of spacing of hid lighting
8 square foot 4x2. a 200 watt floro is not efficient enough for that space. maybe 2 of them but then thats 400 watts of power. better off getting hid lighting
if you were to get a hps and want to add cfls i would add the more blue spectrum to it

good luck