CPU is the biggest issue with this game, adding ram more than 512MB won't even add performance, and the video card you choose for Sims 2 won't make a difference past a certain point which is pretty low end by now.

Your CPU seems good though, quite good enough for this game anyways, despite the integrated chipset you are using you should be fine. If you want any better performance right this second, you could downgrade to 512 ram, because The Sims 2 is weird and happens to improve, just dont remove any more because it only works to a certain point, or at least thats what I have seen in performance reviews of the game.

For spyware use Spybot S&D or Ad-Aware, I use both since that seems to work better and they don't take alot of time to work. Viruses are old news right now, but its possible its an issue, in that case search your services/running applications and look them up and find a way to remove them, anti-viruses just cause more problems than they create.

On another note, don't buy from eMachines?