Definitely get the 4890. It is an incredible deal in slowspyder's post.
check out how it owns All Nvidia in crossfire:
http://i1.techpowerup.com/revi...s/crysis_1680_1050.gif
-Based on this image from Techpowerups review of HD4890 crossfire, the second 4890 is adding a 67% performance boost in Crysis when crossfire is enabled (25.6FPS -> 42.7FPS).
...and its performance when overclocked:
http://images.anandtech.com/gr...042209122109/18835.png
-If you figure 67% performance boost from running two cards in crossfire, then based on this anandtech graph, OC'ed 4890 crossfire would score 62FPS (37.2FPS x 1.67). 62FPS is more than twice as fast as a stock GTX280 in this benchmark (30.9 FPS). You'd get twice the speed of a GTX280 and have completely
fluid 60FPS 1920 x 1200 Crysis for $370 ($185 x 2). You're basically buying HD4890X2 OC performance for ~ $368.00. (just remember you would want that preferably to be on X58, P55, X48, or maybe P45 at the least)