Hmm whats your total data storage up to now ?
But honestly Raid 5 would probably save you time and hassle in the long run. But with SATA6 and USB 3 still not fully supported by most manufactures yet holding off might be your best bet. I don't know if you want to go ahead and pay for 3 2TB SATA3 Gb/s drives when 6Gb/s drive are just hitting the market but then your motherboard has to support SATA6 and even though some say they will; they sacrifice GPU speed supporting it. It is hard choice
But i would probably hold off on it then.