Toshiba and Acer are both good, and those laptops are close in performance as well. The i3 and 520m is slightly better for a slightly higher price but you probably won't notice it's that small of a difference. The amd will have much better battery life if that matters.
I don't think the op is doing anything intensive requiring a i7 and is probably looking at the $450 range. But it doesn't hurt to ask, what is your budget? Is this just for surfing?