This comes around a lot, practically everyone overestimates the size of PSU they'll need. You say you want 600+ watt for breathing room but the HX520 is more than enough that you will have this breathing room. It is up to you and people will probably agree and disagree with me.
the hx520 is 15e more then the tx650 think I'll go for the cheapest option, it just happens that it ends up being the highest wattage of em all (the corsairs I was considering anyway) - Ill live without the modularity(*sp)
If you have room in your case to hide cables then there is no reason to splash out on a modular power supply. The P5Q Pro gives an extra PCI-E slot the P5Q-E gives dual lan and a e-sata connector on top of the extra PCI-E slot. If these extras aren't of value to you then I would stick with the P5Q.
