Lights?

i'm starting a new grow and i'm trying to figure out what type of light i'm going to need for my grow. i'm working on a budget, and height restrictions. my grow room will be 5ft long 4 ft wide and 3 ft tall and will be divided into a veg room and flowering room so each will be 5ft long 2ft wide and 3ft tall. the veg room will be filled with cfls. in the flowering room could i get away with a 400watt HPS or do i need a 600watt. or do i need more? I'm going to do a perpetual ScrOG where each pot will have it's own screen that way I can harvest the older plants with out bothering the younger ones. my pots are 12in by 12in and i'll have 5 rows with 2 plants in each row. I will be useing a 10 week strain that way i can harvest 2 plants every 2 weeks and start 2 new plants every 2 weeks that way i'm constantly harvesting. i'll have an intake near the bottom to get cold air and i'll probably have some frozen bottle water by it to keep the air even colder. and i'll have an exhaust near the top to take out the hot air.

does that sound good and what do you think about the lights?