Apple iMac

General Specs :

21.5-inch: 3.06GHz
3.06GHz Intel Core 2 Duo
1920 x 1080 resolution
4GB memory
500GB hard drive1
8x double-layer SuperDrive
NVIDIA GeForce 9400M graphics

21.5-inch: 3.06GHz
3.06GHz Intel Core 2 Duo
1920 x 1080 resolution
4GB memory
1TB hard drive1
8x double-layer SuperDrive
ATI Radeon HD 4670 graphics with 256MB

27-inch: 3.06GHz
3.06GHz Intel Core 2 Duo
2560 x 1440 resolution
4GB memory
1TB hard drive1
8x double-layer SuperDrive
ATI Radeon HD 4670 graphics with 256MB

27-inch: 2.66GHz
2.66GHz Intel Core i5
2560 x 1440 resolution
4GB memory
1TB hard drive1
8x double-layer SuperDrive
ATI Radeon HD 4850 graphics with 512MB

Source : apple.com