Welcome to RIU!
I like Discount Hydro, let me tell you why, only place I know that will send you a balast overnite for free the first year you have it (if anything goes wrong) and they have a free catalog they will send you full of good info
http://www.discount-hydro.com/
as for the 600 watter can't help I like Ceramic Metal Halide's (only get up to 400 watt)
I second DiscountHydroponics. I get my lights from them cause they have the best deals.
You can get a 600 HPS dimable electronic ballast, bulb and 6 inch air cooled reflector delivered to your door for 360.
Most shops do the ballast for 250 + 80 for a bulb + 100 something for a reflector.
Here it is. You just haveto click on the upgrade to get the 6 inch air cooled reflector or just call them. They are good guys.
http://www.discount-hydro.com/productdisp.php?pid=435&navid=49
Anytime, glad I could help.Great thanks a million!!