The iMac "Core 2 Duo" 2.66 20-Inch Aluminum (Early 2009) features a 2.66 GHz Intel "Core 2 Duo" processor, with two independent processor "cores" on a single silicon chip, a 6 MB shared level 2 cache, a 1066 MHz system bus, 2 GB of RAM (1066 MHz DDR3 SDRAM), a 320 GB (7200 RPM) hard drive, a vertically-mounted slot-loading DVD�R DL "SuperDrive", NVIDIA GeForce 9400M graphics with 256 MB of memory shared with the system, a built-in iSight video camera, and built-in stereo speakers underneath the 20" glossy TFT Active Matrix LCD (1680x1050 native) display.

Connectivity includes four USB 2.0 ports, a Firewire "800" port, built-in AirPort Extreme, and Gigabit Ethernet, as well as a Mini DisplayPort, which supports an external display in "extended desktop" mode.

The iMac "Core 2 Duo" (Early 2009) models are quite similar to the "Early 2008" models that they replaced, with similar external cases -- varying only by a "tapered foot" -- and likewise have the same glass cover that "joins precisely to the aluminum enclosure creating a virtually seamless front surface".

Although clockspeeds and configurations are similar as well, there are a few differences -- the Firewire "400" port on the Early 2008 models has been swapped for an additional USB 2.0 port on the Early 2009 models, Mini-DVI has been swapped for Mini DisplayPort, and the 2009 models also have DDR3 memory (rather than DDR2) with twice the official capacity, improved graphics on the higher-end configurations, and by default, shipped with a smaller keyboard that lacks the numerical keypad.