vintner said:No, it's not the same. High Intencity Discharge (HID) incompases several different types of bulbs/balasts. The box should tell you weather it's a HPS which is better for flowering, or a Metal Haloid (MH) which is better for veg. This is not to say you can not veg with a HPS, or flower with MH, but generally you'll get better results the other way. MH also tend to run a little hotter. Also, you can not mix an HPS bulb with a MH balast or vise virsa.
econolight.com has a 150 watt HPS for about $35 including shipping. It's very easy to turn them into a remote balast grow light w/nothing more than a extention cord and some electricle tape.
Good info Vintner - just one thing to add - the majority of the older security lights are Mercury Vapor and should be avoided completely - unlike Metal Halide (MH) and High Pressure Sodium (HPS) the Mercury Vapor lights are unsuitable for growing at all.
-suga