aqualight pro 150w modification??

[colourfuldog]

I know aquanot has posted similar a few posts ago but I need more info...
I bought the Aqualight pro 150w before they came out with the 250w...
Ofcourse they didn't have that option when I had been looking and now I want to have the 250w HQI's when I need to change the bulbs in the next little while..
Can I just change the bulb and the ballast (from pfo) or do I need to do rewireing inside the unit??
Has anyone done this yet??
I also wanted more blue into my tank overall so is changing my lighting system to all T5HO (8 strip system) better then the above??