Ah yes, the lesson learned by many a reefer. I went from standard 40 watt to PC lighting, finally to MH and have done several versions of that now.
What I'm now running are three 250 watt DE bulbs (2 12K reeflux, 1 14K hamilton) and two VHO actinics.
Good luck and keep us posted, by the way you can find great deals on lighting in the for sale forums from time to time, just be ready to act quick. Also when you get ready to sell you PC system you will take a beating on what you paid to what you will get. Just trying to be honest with you on that part, another lesson learned by many.