"The question that many people have been asking is why do we need 64-bit CPU's?
The answer is that many new applications need to address large amounts of physical and virtual memory. This includes the above-mentioned high-end servers, large databases, and CAD tools. However, this is where AMD's approach is different from Intel's IA-64 approach. Intel has decided that a break from the x86 model was required."
FULL STORY @ PCMECH (http://www.pcmech.com/article.htm?hammer)