A-Tech 4GB (2X 2GB) Max Memory RAM Kit for Dell Optiplex 320, 210L, 210LN, (Minitower, Desktop) - DDR2 533MHz PC2-4200 Non-ECC DIMM Modules at Amazon.com
Refurbished: Dell Optiplex 320 Desktop Tower PC with Intel Pentium D Dual Core 3.0Ghz, 2GB RAM, 160GB HDD, DVDROM, Windows 7 Home Premium 32 Bit (Microsoft Authorized Refurbish) w/1 year warranty Desktop Computers - Newegg.com
4GB 2 X 2GB Memory for Dell Optiplex 320 330 740 745 755 PC2-5300 667MHz RAM (PARTS-QUICK ® Brand) at Amazon.com