, just hope ill have enough wattage!
Here is some info on the 6800 series' power consumption:http://www.guru3d.com/article/radeon-hd-6850-6870-crossfirex-review/4
I'm not that familiar with your PSU but it looks like you'll be okay. Obviously you'll have little headroom leftover.
And as some others have noted, unfortunately your CPU is going to hold you back.
I'm running crossfire with a X4 955 and it requires overclocking to get the most out of the video cards.
AMD chips do have a some trouble keeping up these days.