i've read fragments of this concept somewhere but is it true that XP cannot efficiently use more than 3GB of RAM installed in a system? If so, why? How can this roadblock in a system be removed? The reason I am asking this is because I am in the process of planning a new PC system in anticipation of Intel's Conroe stuff coming out. Its been a while since I upgraded so I really don't know if the 3GB bottleneck applies to 975xx based systems at all. The mobo I am considering is an Asus P5WD2-E Premium and I was looking to load it with 4GB of DDR2-800 RAM. Now, the mobo specs note that it supports up to 8GB but I just need to make sure all the RAM I install can be used by the system. Reading an instance of a 3GB bottleneck in XP got me thinking because, if if it does indeed exist, I want to know before I purchase the PC components. Thanks.