i got a rosewill 1000watt psu for 100 us dollars on newegg to power my 6870xf set up
http://www.newegg.co...N82E16817182188 130 us dollars now, but still a good price i think
Looking at the consumption of a single card on full load = approx 300W and your cpu can take up to 290W at full stress then the answer would be no. Although the 6970s may consume slightly less in Crossfire, I would look at a beefier PSU.
The total power system usage of crossfire 6970's is 596 watts, in the following review:
http://www.legitreviews.com/article/1488/18/
You also need to include CPU and other power usage gear ontop of the usage for the GPU. If its roughly 600w plus your CPU and other things you might be hitting the 700w or more which i dont think will be a good thing in the long term.