Mostly fine for a mid-range gaming machine. Personally I would lay out a bit more for a better GPU, say a GTX 560 or a AMD 6870 because it's the GPU that's going to be the main differentiator when it comes to the performance you're going to get as games these days are more GPU bound than CPU. Also, I'd pay the extra tenner to upgrade to a 500W power supply as this will give you additional upgrade headroom going forward.
The two GPUs I've mentioned will comfortably handle most recent titles at mid to high settings based on a standard 1080p resolution.