The limiting factor is the video card/GPU. You could upgrade the CPU and RAM significantly, but would notice near no improvements in visual output. That said, if you want high quality video gaming capabilities on the go, the minimal model you should even consider is the 15" Macbook Pro.
Dwalls, no disrespect. We are fully aware of what the MacBook Pro would be more capable of providing. However, this thread is about the MacBook and its own gaming abilities. Many users at have shown what it can and can't do. We are aware. However, there are games that the MacBook is more than sufficient in providing a capable gaming experience.
With that said, even the MBP is far from being a complete gaming package. The Mac lineup still has a ways to go before being able able to claim itself a serious gaming machine. However, it has made a considerable leap with the new hardware improvements.
This thread is focusing on what the MacBook can provide and can't in terms of gaming. So lets try and stay on topic please. We welcome any members that wish to provide footage of themselves gaming and a short review of the game performance they had.