600 watts is more than enough, 500 would do.
The 600 watt Silver Power is built on a Solytech platform, pretty much bottom of the barrel as far as quality.
That's not to say that all Silver Power psu's are bad, thier 500 watt unit is built on a Seasonic platform.
Both are damn good and should run any game that you want on high settings for a couple years.
For gaming, they're about equal. The 965 is better in some games and the i5 is better in some games. Generally when the i5 has the lead, it's by a slightly larger margin (still small), as some games utilize Intel's architecture better. When the 965 has the lead, it's usually very small. An i5 might hold up slightly better in future games if you choose to upgrade to a more powerful GPU, though both will likely still be exceedingly close in gaming performance. If you overclock, the i5 is a little faster clock for clock. It's not as enormous as it may appear due to turbo boost (excellent feature if you aren't into OCing, btw), but it still will run about 5-10% faster than a 965 if they're at the same clock speeds. In real-world terms, there isn't really a noticeable difference between either CPU.
An i5-750 tends to be about 5% better on average across the board for non-gaming professional applications, for encoding, ripping, etc.
My best suggestions is to go with your gut. If you initially were leaning for AMD, then get the 965. If you were initially leaning towards Intel, then get the i5. You'll be very happy with either one.