ATI Catalyst 8.9 vs 8.8 vs 8.7

Assassin's Creed, Call of Duty: Modern Warfare and Race Driver Grid don't get any benefit from the driver on Windows XP x86 or Vista x64. The performance in Crysis Warhead on the other hand is increased by 11 percent compared to the Catalyst 8.7 and 8 percent compared to the Catalyst 8.8. We confirmed the result with a quick test in the original Crysis.

Therefore the Catalyst 8.9 is recommendable for both operating systems if you want the performance benefit for Crysis.