Would this light be be ok?

Hi people I'd be really greatful if someone can help me chose a grow light.. I've been looking at this bulb since it says its good for both veg and flowering does anyone have any idea if this would be any good? is it a HPS one? Also I'm a bit confused.. it says something about a reflecter and ballast; the reflector is the thing that reflects the light and the bulb fits into and the ballast powers it right? could anyone point me to any suitable ones on that website or recommend any better (400w) ones even complete kits it would help a million thanks I tried to find info in other posts about where to get lights and this kind of thing and couldn't find anything maybe I'm just daft lol

+ Would I be best going with a bulb like this or opting for a light system in which you can switch the bulbs? if so if you could recommend one!

http://www.growlightexpress.com/grow-light-ballasts-3/400-watt-ballasts-12/sun-system-10-400-watt-hps-ballast-24.html
http://www.growlightexpress.com/grow-light-systems-2/sun-system-2-hps-400-watt-7.html

www.HTGSupply.com has a good assortment of equipment, you can find a light setup complete with ballast, reflector, and bulb - to fit whatever your budget is. The bulb you are looking at would be fine, however, you cannot put it in a regular light fixture - it requires a special ballast.
Good luck!

got my 400w hps for htg supply for like $130 got it in 7days works great. Just bought a MH conversion bulb from them for $50.

Thanks for the replies I'm buying the light next month I'll keep them in mind, does anyone have any idea how many plants I could grow under a 400w HPS? I was thinking maybe three?

i did 6 girls under mine.