lighting question...will this work?

I am planning on upgrading my lighting to metal halide. I visited 1000bulbs.com, and they seem to have very good deals on ballasts and bulbs...i was wondering if anyone coulod tell me if the 175 watt ballast i am looking at would be acceptable, i would most likely buy two. also, what else would i need to finish the set up, i know i would need to house it in something, but i'm not quite sure what all i would need besides the ballast and bulb. Thanks.

Here is the ballast: http://www.1000bulbs.com/product.php?product=922

there is also the same wattage ballast that says multi-tap, but i do not know what the difference is...any help would be greatly appreciated...THANK YOU.

http://www.1000bulbs.com/product.php?product=617

and the combo: http://www.1000bulbs.com/product.php?product=11276

Thanks, Ryan