The Q6600 is still a fine processor for the vast majority of people, so I wouldn't look to replace it. You can get by with 4GB of RAM. 8 is now recommended, and RAM is super cheap. Yet no need to run out and get some right now. The GPU looks to be your glaring weak spot, especially if you do any gaming. If no gaming, your GPU will get you by for most regular stuff unless you use CUDA enabled programs (if you don't know what CUDA is, it's does calculations by the GPU instead of CPU....Google it). If neither of those, you are probably fine the way you are. I wouldn't look to upgrade (outside of RAM) for 2 or 3 more years unless you start doing really heavy CPU and/or GPU calculations on a regular basis.