When it comes to building PCs I am very much a noob as I have grown up exclusively around Macs, unfortunately I cannot afford them anymore. I plan on building a casual gaming PC and wont be doing much more than internet and gaming.
Here is what I have come up with and believe that they will all work together but insight would be appreciated.
intel core i5 3570k LGA 1155
AsRock z77 extreme 4 ATX motherboard (LGA 1155)
ASUS Radeon HD 6670 Graphics Card
Corsair tx650 power supply
LG Blu ray optical drive
Corsair Vengeance Ram 8gb (2x4gb)
Seagate Barracuda 1TB internal hdd
Cougar Challenger Case for ATX motherboards
The thing that immediately springs to mind, is that it is a basically good build, with a weak graphics card. I suppose it depends on what you mean by casual gaming, and, if you had mentioned your monitor resolution, it would be easier to give constructive advice. There is nothing WRONG with the build, if you don't want to overclock, but in that case you don't need anything like 650w power supply. Perhaps a smaller PSU would free some money for a better graphics card? If you DO want to overclock, you could still reduce power supply, but would need to add an aftermarket cooler, for CPU, and use low profile RAM. If you can give some clarification, on these points, together with any budget limitations, it would be possible to give more detailed advice. It would also be helpful to know roughly where you are, for sourcing any suggestions.
^ Like he said. You could surely get a 500w PSU and get a better graphics card. With the new generation graphics coming in so quick in games like Watch Dogs etc. That graphics card (6670) won't hold you for long!
We highly recommend you get at LEAST something like a 6850!