Apple iMac (2008 Edition) review: Apple iMac (2008 Edition) - CNET
How do the "Early 2009" Aluminum iMac Core 2 Duo models compare to the "Early 2008/Penryn" models that preceded them?: EveryMac.com
How to Upgrade iMac RAM (20" and 24" Aluminum): EveryMac.com
parts-quick Memory Module 4GB 800MHz DDR2 (PC2-6400) - 2x2GB SO-DIMMs for Apple iMac Intel Core 2 Duo Early 2008 20 inch 24 inch and White MacBook Mid 2009 13 inch Brand at Amazon.com