I'd go with the 600w over the 400 or the 1000. 600w will be sufficient lighting for a few grows, and you can always add another 600w when you can afford it/decide you need it. I use 600 watters, and with an aircooled hood with a decent exhaust fan I don't have problems controlling heat. With my hoods around 8" from the canopy temps at the canopy are at a very comfortable 78-79 degrees.