Yes, the system ram and GFX card is pretty much as good as you can get, the CPU will limit your performance though (refer to the Techspot benchmarks). That is only in more demanding game setups like 4 v 4 and games with massive supply limit armies, otherwise youll be more than fine. Unfortunately AMD CPUs aren't as good as the newer intel chips in this game, but the reviews show that overclocking has significant benefits (nearly every percent overclock translates to a % increase in fps). Id say , based on the reviews ive seen, worst case scenario (which doesn't happen often) you might see fps in the low 20s which isn't bad, still playable. If it bugs you just lower cpu depended settings like reflections and/or physics (trust me you will not even notice they are lowered/removed). With the exception of these infrequent situations which are not that bad you should have pretty much flawless performance.
btw you can play with 4xaa & 16xaf too and still have great fps. I pretty much have the exact setup you have (except for a triple core Rana @ 3.0ghx which is slightly faster, SC2 only take advantage of 2 cores)