Your system meets the requirements, but the processor and RAM both are at the minimum. Your graphics card actually probably is the best part compared to their specs, which is common for MMOs. You might benefit from getting another GB or 2 of RAM, but it shouldn't be needed. Also, since it's entirely online with alot of players at the same time, your likely to run into lag issues with your internet speed long before your computer's speed causes a problem.
In short, you could use a small boost to be sure you run the game as smooth as possible, but I don't think it will be needed.
Well, APB does have higher requirements than WoW, so it might need to be put at lower settings than you had for WoW. For RAM, the brands that Futureshop carries are pretty similar in quality and reliability. Kingston is a bigger name with a much longer track record than the others, though. To install it, there is a short video with tips here. You can always bring it in to the store if you change your mind.
