Hey,
If you're getting a new PSU, get something a bit more powerful, like a 650 or 750w PSU.
As for the GPU, if you are not planing to OC on your own then get the superclocked. If you're NOT planning on OC'ing it yourself and cant really decide - then yes! Asus IMHO has better cooling solution overall , so i would go with the ASUS and try to OC it yourself : )