Grow lights wattage - to plant ratio

Hey everyone, i'm new to these forums and am interested in starting a garden of my own. I have a quick question, does ayone know how many plants i could fit in a 5x5 inclosed grow space. (with the plants being abe to grow to full potenial) I would be using between a 400 - 600 watt MH/HP lamp.

I am thinking 3-4 I use 2 1000 watts hps and have 6 under each

you can grow about 6 plants under a 400w if rotated frequently, if not you will end up with one or two nice plants and the rest will be stretching for light