From a comparison here: http://www.cpubenchmark.net/compare.php?cmp]=2020&cmp]=2252&cmp]=1781
The i3 will be faster than what you have now, getting a better CPU won’t improve your gameplay as much as getting a better graphics card, but there’s a point where the CPU can slow everything down so you kind of want to keep them at a similar level.
As far as that AMD processor goes, it’s slower on single-core operations and since it’s a completely different system you’d have to upgrade your motherboard as well to be able to use it.