I know this is going to sound weird but, is there a difference between having a 4 bulb fixture or a 2 bulb fixture? It seems the 2 bulb ones are alittle cheaper but I want to get a good one. I will need to get a 48" fixture. Any thoughts on that? I will add one thing, The 2 bulb one did'nt have seperate on/off switches, which I think is a good idea.