PC ballast is fine, get yourself some higher end bulbs for it though.
MH ballasts from odyssea are not good at all, take it from me, i used it for a year and wished i hadn't now that i see the difference. It produces the wrong spectrum for good color and strong growth. it is easy to pick yourself up a new ballast from ice cap. some people can help you with that
but other than that, GREAT deal. I'd up your ballast power to a 2x250 watter though if you are doing a 90 gallon tank, that is a lot of depth to penetrate and youll have much more fun with that higher wattage ballast in regards to the coral choices you'll have and where u can place them.