No, you can't. However, WATTS is measure of POWER CONSUMPTION, NOT light output. Those 4 24W T5 lamps will produce a LOT more PAR for your tank then 96W of PC light could ever dream of. That fixture has reflectors that direct the light from all 360 degrees of the T5 bulb into the tank, a PC fixture at best, puts less then 270 degrees of bulb area into the tank, and that is only if you have reflectors for each of the bulbs, which I have never seen.

Have you ever seen a T5 fixture and a PC fixture side by side? The difference is staggering!