I have an early 2009 24" iMac with a Radeon HD 4850 video card. Within windows I can go the display section of the control panel and select to view all available modes. It shows 1920x1200, the native resolution as being available at 60hz. It shows 1920x1080 being available at various refresh rates all the way up to 1920x1080@120hz. When I select this option the movement of the mouse seems to be more fluid. The only thing I can't seem to figure is how to select a refresh rate along with the resolution for a game. I would like to be able to play Borderlands in 1920x1080@120hz, but I when I select that resolution it defaults to 60hz. Can anyone offer advice? Also, I have not seen any other mention of people using the imac in 120hz mode. Could I possibly cause damage to the screen?