On my Trigon 190, I wasn't happy with the standard lamps. The tubes didn't evenly light the tank. I replaced it with an Aqua Medic 70w Metal Halide. Pricey, but it looks nice and as it's in the living room I went for it.
On my 6' tank, I put 3 70w MHs that I got from Fast Light (Fast Light Nano Metal Halide). It's not the most stylish looking but as it's in my fish room, who cares And they're way cheaper than the Aqua Medics.
If you like them, you have to ring the order through to get 5200k lamps. They are geared towards Marine Lights on the web page