If you see a significant need to buy the stuff, buy it. I would call a significant need the point where you couldn't play new games anymore, or everyday computing tasks make the poor box slow to a crawl, but that's just me. Anyway, there's no way any of that should be happening on your rig.
Well Supreme Commander was reviewed in PCGamer and it says the more cores on a cpu the better the game plays, and also that it eats up memory, and the more the smoother the game is......It is the first true next gen game engine where it actually uses all this new hardware available, it is multicore enabled, and can use endless amounts of memory, and a killer sound card with memory all helps the game play at it's best