The 500w has 28a on the 12v rail. The 600 has two 19a 12v rails. The 500w is bronze so will be a little more efficient. Either one would work.
I think that was supposed to me 38 the other has 35(interesting that the 600 watt delivers less power on the 12 volt rail, but common with older designs, this is not as bad as many I have seen). It is a trivial difference at best and both are more then able to run your system.
I would personally get the 500(with its 5 year warranty vs the 3 year on the other unit) watt because it is a newer design with auto voltage range and all that good stuff.