I will be using the i5 2500k possibly oc'd and the evga gtx 570 superclocked to 797 Mhz. What wattage will be required? Are there other components im not listing that influence the psu like hard drive mobo fans etc etc..?
Use the PSU calculator here: http://www.extreme.outervision.com/psucalculatorlite.js... and then choose a quality PSU, not just something cheap. A quality modern PSU has full range active PFC (no little voltage switch) and some level of 80+ certification for efficiency. Seasonic, Antec, Corsair, XFX, and Enermax/LEPA are among the better brands.
The X-750 is modular and more efficient (80+ Gold rather than Bronze), but all of those PSUs are actually made by Seasonic (they make the PSUs for XFX), so any of them would be a good choice for your system.