As mentioned already, many have had decent results with the stock power compact bulbs with softies or LPS. The biggest factors with the power compacts are keeping the bulbs changed out and possibly heat issues, but they still can get the job done. I even knew someone who was keeping SPS towards the top of the tank with good results under stock lighting.
The best bet for new lighting, if you are looking to keep the hood intact, would be an LED retrofit. Something like the Steve's LED retrofit listed above seems to be a fan favorite. Otherwise you could get the parts and build your own to put in it if you dont like the turn key approach and want to cusrmtomize it more to your liking, but the Steve's kit does get good feedback.