So in summary - A PhenomII 965 and a GTX660, basically.
Nvidia say a 450W PSU for a GTX660, but in reality you are unlikely to even touch 300W.
Personally, I wouldn't have bought the Coolermaster PSU. It's pretty poor quality and you can probably do better for around that price. As you've got it though, it should be ok as it's well within its limits but don't try using anything much more powerful or you might run into problems.
Their specs can be pretty confusing. The theoretical maximum power draw of a GTX660 is 140W.
How much you are actually drawing will depend on how heavily you are using the card.
The current rating is supplied because a lot of older PSUs spread their power across 3.3, 5 and 12V, meaning that you might only get 200W or so of 12V power. 24A means that the 12V supply is capable of 288W, a much more realistic figure for a total power draw for a PC using that card.
The reason they overestimate the amount of power you need in a PSU (the 450W figure) is because a lot of PSUs (especially cheaper ones) are not capable of delivering the amount they state.
A good 400W PSU would run that system without any issues whatsoever. Your 500W PSU is a little questionable in terms of quality, but it should work given how far it is above what you actually need.