I just went out and bought a sun systems 10 400 watt hps for my closet and i leave the doors open one small fan and one box fan in with it and it heats up my room pretty good. And Its very very bright!!!
Lots of variables to consider like size of your growspace, ventilation and seed strain. Sure you can grow some autoflowering dwarfs and get some bud, but you are not going to grow a monster with one 150w HPS.