4GB 2 X 2GB DDR2 Memory for iMac 7,1 Mid 2007 20" inch 24" inch Intel Core 2 Duo 2.4GHz PC2-5300 667MHz 200 pin SODIMM (MemoryMasters) at Amazon.com
4GB [2x2GB] DDR2-667 (PC2-5300) RAM Memory Upgrade Kit for The Apple iMac 7,1 (20-inch, 2.0GHz, MA876LL/A) Intel Core 2 Duo (Genuine A-Tech Brand) at Amazon.com