Hi Rob: If your sink is "porcelan coated", I take it its a cast iron sink. Now how aggressive you get depends on whether you want to save it or not. and whether you care about the tile counter top. If this is a total remodel and the existing kitchen is going into the dumpster, then a 5 lb sledge and a 2 inch cold chissel will do the trick, It you want to spare the countertop, I would put a large piece of wood on the cabinet floor under the sink, put a bottle jack on that, put a 2X4 or 4X4 vertical between the botton of the sink and the jack and lightly jack up, then tap the blade of a stiff 3 or 4" putty knife under the lip of the old sink, around its entire perimeter and keep putting more up pressure on the sink until it finally comes lose. In all of this, I presume that you have all plumbing lines disconnected.