The 24″ 2.66 GHz model includes 4 GB of RAM and a 640 GB hard drive. 256 MB of system RAM is dedicated to video.
The 20″ iMac has 2 GB of RAM, a 320 GB hard drive, an 8x SuperDrive, Nvidia GeForce 9400M graphics, and Apple’s aluminum keyboard and Mighty Mouse. They support up to 8 GB of RAM and are the first iMacs to use SATA optical drives. The March 2009 iMacs have four USB 2.0 ports (one more than before), FireWire 800 (but no longer 400), gigabit ethernet, 802.11n WiFi, Bluetooth 2.1+EDR, and an 8x SuperDrive – as well as a slim keyboard with two USB 2.0 ports. (ATI Radeon HD 4850 is a build-to-order option on the high-end iMacs.) The low-end iMacs use the same Nvidia GeForce 9400M GPU found in current MacBooks and the new Mac mini, while the high-end iMacs use GeForce GT graphics.
Apple has updated the iMac with Nvidia graphics as a standard feature ( the Early 2008 iMac used Radeon graphics, although there was an Nvidia GeForce 8800 GS build-to-order option for the 24″ model).
