Watts per gallon is not a reliable rule.  Different types of lighting produce different light intensities.  For example, 250w of NO fluorescent is not the same as 250w of PC fluorescent and neither is the same as 250w of MH in light intensity (PAR).
Most soft corals and a good number of LPS will thrive under PC lighting.  You may find that you need to keep some of them in the mid- to upper- part of your tank for them to be happy, but you could keep a variety of soft and/or LPS corals.  We have 260w of PC and 80w of NO on our 90g mixed reef of softies / LPS and it has been doing quite well.  I find myself fragging our toadstool leather and xenia often, and the couple LPS corals we have look better than when we bought them everyday.
How old are your light bulbs?  If they are > 6 months, you should consider replacing them before adding any corals to your tank.  Even though the bulbs still light up, they lose intensity over time and the color spectrum they produce can shift.  PC bulbs are good for 6 - 8 months, although some have stretched them out to 9 - 10 without too many problems.  Once you have corals in your tank, it's normally recommended that when changing out light bulbs, you change them on a rotation and not all at once (change one bulb this week, the other one next week).
Otherwise, keep your water parameters in check (calcium, magnesium, alkalinity, and nitrate) and good luck.