Help is my power supply good enough?

So i just got a new build and the problem is that i did not have enough moeny for a new power supply so i stayed with my old one which is a 620w vantec ion2.

The thing is that it only has 22amps on the 12volt rail, but it also has another 12volt rail with 22amps with a max wattage of 444w on both the 12volt rails.

I read some where that a gtx 670 needs atleast 30amps on the 12volt rail.

So is my power supply good enough to run the gtx 670 overclocked and a intel core i5 3570k overclocked.

And what is the deal with double rail power supply, what are there total amps?