Asrock p67 or z68

Performance-wise there should be no difference, but on a personal note I prefer the Z68 over P67 just for it's ability to work without a dedicated video card.

It all depends on what you plan on using your computer for. Without that info, nobody can give you an honest answer.

ok, well I will have a gtx 580, does that help?

That does help. If you don't intend to use SSD caching then the two should have similar performance. If you're thinking about using a SSD to cache your HDD(s) then the z68 is a must because the p67 chipset lacks SSD caching. Also, Quicksync doesn't work on p67.