Need Lighting Suggestions For 125 Gallon Tank

I am in the process of setting up 125 gallon plant tank.  It is 72 inches
long, 18 inches wide, & 20 inches tall.  I was thinking of using 8 standard
T8 bulbs staggared which would give me a little over 2 Watts per gallon.
Would it be more cost effective in the long run to use a 250W metal halide
setup?  Would one MH bulb provide enough light to cover the entire length of
the tank.  What kind of lighting configuration do most people use with this
size tank?  I am open to any and all suggestions.  

        Thanks in Advance

        Tom Roberts
        Phoenix, Arizona