lighting ??

i am planning on taking out my fluros of my veg room and getting some mh lighting. my question is the room size is 4x3 x 4ht is a 250 watt going to be enough for that area or will i need more or could i get away with using less?

yeah thats the one problem i have switching, the fluros are spread out and light evenly. i was either going to get like 2 150watt or the 1 250 and set up some secondary light to fill the gaps.