First, you must buy new ballasts as your normal output bulbs have normal output ballasts so to speak; I'd recommend measuring the length of your tank and buying a new setup, preferrably one by Current USA (the Orbit model is schweet!).
LPS means "long polyp stony". These are corals with hard exoskeletons and long fleshy polyps. Good examples are the frogspawn, hammer and torch corals. These corals require PC lighting and low to moderate water flow. I have a tank with nothing but LPS and softies and I run a single powerhead to move my water around. LPS corals typically eat meat and can be spot fed whenever you want; they grow much faster this way, trust me!
Softies are corals with no skeletal base; they are soft. Good examples of softies are zoanthids, mushrooms, leathers, xenis, etc. They do well under PC lighting and low to moderate flow. I have two toadstools, a cabbage, eight types of zoos, star polyps, tons of softies. I think they're cool as can be so I get as many as I can.
If you get a Current USA light fixture (the Oribt model), you will get both blue (actinic) and white bulbs and can keep any LPS or softie you want. Stay away from SPS and clams as they require MH and heavy flow. Hope that helped!