how much performance gain would one see from upgrading to a amd 1055t frm.......

from a amd 720 x3

what kind of applications will you be using it for? For multithreaded stuff and multitasking there would be a pretty big difference, for gaming not so much. If you are gaming I would upgrade your video card instead.

it depends of what your doing. if your encoding decoding or compressing files the extra cores will be better if your looking at gaming or just browsing web and other basic 2d tasks focus on clock speeds. and video card as stated above.