Hey buddy, these guys are just messing with you. You really need to research a lot before you go and do this. I haven't started yet and I have been researching for a REALLY long time. This will help you out a lot
http://www.marijuanapassion.com/forum/showthread.php?t=9396
Click on the first link, the marijuana passion free grow guide. Give a read through those sections. I would pick up a book also from the library or go and buy one with cash at your local barnes and nobel or whatever. Look for this book
http://www.amazon.com/dp/1878823299/?tag=skimlinks_replacement-20
I have the indoor outdoor bible. *its really good*
To answer your question... A 175 watt bulb will be plenty for you. Really what you do is keep the 175 watt within a foot of the plant at all times. Put it really close, put your hand on the top of the plant, if you burn your hand after 10 seconds the light is too close!
As far as where to get the metal halide from and which to buy, I'm in the dark. I've asked but I think the community wants me to do more research. In my book I believe it hints at 5500K or 5600K and up is great for vegatative growth, but don't quote me on that! If you want to do the whole stage from start to finish I would suggest getting two different bulbs, the metal halide for vegatative and then a 150 watt hps bulb. You need to make sure that your ballast can support both types of lights.
Also the Search function is REALLY useful. When you login to the forum you can see a blue bar near the top. It says user CP, Members List, Gallery, Resources, Arcade, New Posts, Search, etc. etc. Click the search then advanced search. You will see at the top left a box that says keyword in it and then a box to the right of that. The box on the right says user name. The box below the user name has a bunch of different parts of the forum in it. You can narrow down your search by typing in generic things like, metal halide and then click on the lights section. The lights section is somewhere in the list (Below the user name box) Then scroll down and hit search now. Then you can read through all the posts! At the bottom of the page you will see a next page arrow too! I advise you to just type in my username and hit search. I want to do a one grow setup and you might find some useful info in some of my posts.
GOOD LUCK!