parts-quick 8GB (2 X 4GB) DDR2 Desktop Memory PC2-5300 240 pin 667MHz Non-ECC DIMM RAM at Amazon.com
CMS 8GB (2X4GB) DDR2 5300 667MHZ ECC Fully BUFFERED DIMM Memory Ram Compatible with HP/Compaq Workstation Xw8600 Series Ddr2-Pc5300 Fb for Server Only - B54 at Amazon.com
Micron MT36HTS1G72PY-667A1 8GB Server DIMM DDR2 PC5300(667) REG ECC 1.8v 2RX4 240P 1024MX72 DDP 1GX4 at Amazon.com