750 watts is good for that setup and i also recommend a rosewill capstone PSU as thats what i have been running for 8 months with everything oc'd and i have had 0 problems.
Also remember that the more amps on a 12 volt rail the better. If you have a 1000 watt psu and 20 amps on the 12v rail you would be better off with a 500 watt psu with 40 amps on the 12v rail. The psu i linked to has a massive 62 amps on a single 12v rail thats a really good number.
The RM750 is a corsair psu and if I remember most of the XFX power supplies are made my Seasonic. I'd go with the XFX Pro over the corsair RM series as the quality seems better. Although for that build a really good 650w could be better like this Seasonic unit: http://www.newegg.com/Product/Product.aspx?Item=N82E16817151118