lighting ... suggestions pls
 

Soooo ... now I've decided that my 90 gal tank will be a reef tank I need to decide on some lighting, I'm weighing towards metal halide combo lights as I want to keep a variety of corals and dont want to be limited in the future. My dilema is how many watts do I need ?
should I go with the 2 x 250 or will 2 x 175 suffice ?

I would go with the 250's. As you said you don't want to be limited in the future and if you decide to go with SPS you'll be glad you have more wattage. Also if your tank is a standard 90 gallon, they are quite tall and you'll want lots of light getting to the bottom of the tank.

i also agree, just go with the 250 right from the start.

x3 on the 250's :)