To clarify, an MCP is an individual who has been able to gain Microsoft Certified Professional status meaning, the MCP is qualified regarding his knowledge of Microsoft products and solutions. However, the MCP acronym is an all-encompassing term to refer to a wide variety of Microsoft levels of accreditation.
To become a network administrator support MCP, one may have to train for MCSA level first. MCSA stands for Microsoft Certified Systems Administrator someone who has intimate knowledge and skills in the Microsoft Windows OS network system. You know someone has MCSA level skills if he can do effective management and troubleshooting of that specific network system.
The MCSA accreditation is further subdivided into two forms of accreditation. One is in MCSA for Windows Server 2003. The other is for MCSA in Windows 2000. Pretty soon, there will be a third which is Windows Server 2008 certification (which is expected to be the next stage of certification from Windows Server 2003 accreditation standards.)
By pursuing MCSA accreditation from a licensed accreditation provider, you gain recognition from Microsoft itself as to your capabilities. You become more valuable to your present employer (and may even catch the eye of industry headhunters who are always on the lookout for talent.) All MCPs (whether MCSA or otherwise) gain the added advantage of belonging to the Microsoft community of MCPs who may prove advantageous to know for your career, or for personal reasons.
It is always good to have a network administrator support MCP around so that if you lose your present MCSA network administrator (due to employee attrition, retirement, or other means), there will be someone to step in to fill the position quickly and easily.