Crucial 4GB DDR2-667MHz (PC2-5300) CL5 ECC RDIMM DR 240-pin Server Memory CT51272AB667 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
HP 16GB 2X 8GB PC2-5300 DDR2-667 2Rx4 ECC Fully Buffered FBDIMM Memory Kit (HP PN# 413015-B21) at Amazon.com