Headlight conversion

I know theres a few topics on the board about H4 headlight conversions, but I've been unable to piece together exactly what I need to do the conversion. From what I understand, everyone tells me to get the casing from http://www.autooptiks.com but what watt bulb should I be getting, and what is the best brand that won't blow out and will look the nicest? Also, are there any other parts necessary to do this conversion, and what's a general figure as to how much everything should cost? Thanks