Don't SLI or Crossfire just yet. The 4870x2 for $480.00! An amazing deal if you ask me.
http://www.bestbuy.com/site/olspage.jsp?skuId=8986225&type=product&id=1218005635566
http://www.bestbuy.com/site/olspage.jsp?skuId=8986225&type=product&id=1218005635566