Symmetric multiprocessing

Symmetric multiprocessing (SMP) is a technology that allows a computer to use more than one processor. The most common configuration of an SMP computer is one that uses two processors. The two processors are used to complete your computing tasks faster than a single processor. But Two processors canot give you double the processing speed of a single processor.

In order for a computer to take advantage of a multiprocessor setup, the software must be written for use with an SMP system. If a program isn’t written for SMP, it won’t take advantage of SMP. Not every program is written for SMP; SMP applications, such as image-editing programs, video-editing suites, and databases, tend to be processor intensive.

In the Windows XP family, only XP Professional supports SMP. I guess that may be the reason why XP boots and works faster than many other Operating Systems.