Last Updated: 3/22/2003 Memory always confuses the shit out of me since they update so quickly: 3 Types Right Now seemingly: SDRAM - obsolete DDR SDRAM - next generation sdram is ddr, double data rate - synchronous with teh system clock - so instead of a SDRAM 133mhz system bus speed, DDRAM can go up to 266Mhz. RAMBUS DRAM - Needs special motherboard. RIMM (Rambus Inline Memory Modules) / CRIMM (Continuity Module) must be filled in all the slots. Available in ECC or Non-ECC format. http://www.dewassoc.com/performance/memory/ddr_sdram.htm