GeForce Forceware 266.58 Windows XP | 7 | Vista are out for grabs.

Performance

Increases performance for GeForce 400 Series and 500 Series GPUs in several PC games vs. the latest Release 260 drivers. The following are examples of some of the most significant improvements measured on Windows 7. Results will vary depending on your GPU and system configuration:

GeForce GTX 580:

o Up to 7% in Battlefield Bad Company 2 (1920x1200 4xAA/16xAF)
o Up to 12% in Battleforge (SLI 1920x1200 4xAA/16xAF Very High)
o Up to 11% in Call of Duty: Modern Warfare 2 (SLI 1920x1200 4xAA/16xAF)
o Up to 7% in Dirt 2 (SLI 1920x1200 4xAA/16xAF)
o Up to 7% in Far Cry 2 (1920x1200 4xAA/16xAF)
o Up to 5% in Just Cause 2 (1920x1200 4xAA/16xAF Dark Tower)
o Up to 5% in S.T.A.L.K.E.R.: Call of Pripyat (SLI – 1920x1200 4xAA/16xAF)
o Up to 9% in Stone Giant (SLI 1920x1200, DOF on)
o Up to 8% in Unigine Heaven v2.1 (SLI 1920x1200 4xAA/16xAF)

* Improves performance in Final Fantasy XI on GeForce 400 Series and 500 Series GPUs.

Visual Quality

* Adds ambient occlusion support for one of the most popular games of the year: Starcraft II: Wings of Liberty. Ambient occlusion improves the quality of lighting, shadows, and depth perception in many parts of the game.