HPS will definitely work but like you said... keep a few cfl's that are 6500K in there with the HPS to balance out the color of the light. HPS tends to put out more of a orangish/red color of the light spectrum which is best for flowering, Metal Halide is better for vegging since it puts out mostly blue light which is good for leaf, root and stem development. HPS is good for flower/bud development. Some people use HPS from start to finish just make sure to balance out the light spectrum(hint: wutever you do dont use plant/grow bulbs) go do some research in the Newbie Center... they share alot of wonderful information for begginners there!! Including... grow room set-up, info on different lighting and lighting systems, basic nutrient information, problems to look for and a bunch of other great stuff! a lot of experienced and knowledgable people here to get you thru your grow... and the best part is they are all willing to help!