To be honest, you already have everything needed to produce quality tracks as everything can be done in software these days. But its all down to personal preferance and money! One thing you are deffinately going to need are a decent set of monitors, as these will really help your production. If your going down the software route, then get yourself SX, FL studio, Wavelab, Soundforge, V station, Bass station, Z3ta, waves plugings pack, and anything else you stumble across. If you are going down the hardware route then its going to be expensive. You'll deffo want a Desk,(maybe a beringer), Synths,(Virus c?),midi controller,(evolution?).

Really you need to specify what budget you are working on. And one piece of advice i can give you - Get to grips with some software first, and get to know what you like and want. Then you can decide what to shell your hard earned cash on.