Eh. Both are pretty bad (for BF3 at least), but upgrading your GPU for now might help performance a bit (don't quote me on that), but upgrading your CPU and GPU will definitely help performance. And uh, if you can ever scrape up the money for it, I'd upgrade to 8GB of DDR3. I've never really used DDR2, but from what I've heard, it tends to be a lot slower than DDR3. And when I play BF3 I usually hit up to around 4-5GB of RAM usage, so it's always nice to have to some headroom.