Windows XP and Symmetric Multiprocessing
Symmetric Multiprocessing (SMP) is a technology that allows a computer to use more than one processor. The most common configuration of a Symmetric Multiprocessing computer is one that uses two processors. The two processors are used to perform the functions for the calculation faster than one processor. (Two of them are not necessarily, but they are twice as fast as a single processor.)
A computer that has more than one processor, the software must be written for an SMP system. If a program is not written for the Symmetric Multiprocessor, it will not take any advantage that the SMP offers. Not every program is for the SMP. SMP applications, such as programs for image editing, video, and databases are usually CPU demanding.
SMP in Windows XP
Operating systems are also written for Symmetric Multiprocessing so they can use multiple processors. In Windows XP, only XP Professional supports SMP, not XP. If you are a consumer with a dual-processor PC at home, you need to have XP Professional installed. Windows XP Advanced Server supports SMP as well.
In the big scheme of Microsoft, XP Professional is meant to replace the old Windows. In fact, XP Professional uses the same kernel of Windows 2000. XP Home is a replacement for Windows ME, and Windows Millennium Edition does not support SMP.
The difference between XP Professional and Windows XP Home is a lot more than just about $ 100 and SMP. XP Professional has many other features that are not in XP Home. Some of them you may use, but others you might know now about or not even want to use them.