Honestly, you are green..new to photography. The worse thing you can do is spend money on something now and in 3-4 months, realise that you should of purchased something better / different. You lose money that way.
You dont know what you like to shoot, how you like to shoot. So while this lens is better than that lens discussions can go on forever, I'd highly suggest picking up the 50 1.8 and going on with that.
You can do some amazing work with just that lens. Give yourself some time with that lens and save up money as you learn. Then, when you are more comfortable in knowing what YOU need and what YOU like, put the cash down on some quality glass.
People are all about the technology. But really, its about the photographer and the knowledge. The technology is a tool and too often, its a crutch