One of the most critical purchasing decisions you can make when building or upgrading your computer is selecting the right memory. While a memory module may be a true PC2100 / 266MHz DDR, the specifications, quality and performance can still vary significantly. The items listed below conform to a wide range of performance, quality and customer support criteria. By selecting an Atlas Precision Memory module or using the 'Memory Configurator' to select a system specific upgrade, you are ensuring the greatest level of performance, reliability, compatibility and product support.