Cyberpower... NOOOOOOOOOOOOO!
We can help you put a better, cheaper build together.
But if it must be Cyberpower, if you can stretch for 2x6950, go ahead and do crossfire. If not, get a single 6970. 2x6850 is probably similar in performance (maybe a little better) than a 6970, but if prices and performance are similar, single card is always the better option.
But there's a rumor AMD is releasing their 7xxx series cards (at least some of them) before the end of the year, so it might not be a bad idea to wait.