CPU: Well, damn, that's a good CPU so no need to worry about a bottleneck there 8)
MoBo: I will admit i am not as familiar with Intel MoBo's and chips as i am with AMD, but assuming the p45 Pro you are using supports Crossfire, then this should be fine. You really will want to check it (or if someone could chime in and say whether or not it does?)
PSU: Antec is a good brand and 650 watt should be more than plenty for either GPU option here. Although we could assume you have the necessary power connectors given the high wattage, it would still be good to check. The Saphire brand 4890 Toxic i see uses an 8pin and a 6pin. Where as the 4770's would each use a 6.
Overall, if you want to not deal with crossfire or you can't then the 4890 is a good choice. If you want to use crossfire and don't mind it, then the 4770's are better and will provide you with really good gaming power.
You still may want to consider waiting until the newer 5xxx series stuff comes out because one of those would be even better performance, or the older stuff should become cheaper.
so, if you don't mind xfire, and the mobo can handle 2 GPU's then
2x 4770 > 4890
if you already have a 4850 or a 4870 or something you could also just buy a second one of those instead and xfire them.