Do you plan to use the entire floor area to hold plants? If so you are way short on light with either of those set ups, you should be looking at 6 600s or 6 1000's. That is based on the basis that a 600 covers a 3x3 and a 1000 more like a 4x4, for optimal lighting for growing. So you take your 8 x 15 room and break it down into 4x4 squares you end up with 2 rows of 3 to 4 squares a piece. Light movers could help to reduce the number of lights needed, but i do not think you would get much (of your) area out of 4 400's or 2 1000's. If that is all the light you can afford for whatever reason, i would consider adding a wall or partition of some sort.