As it is doing on the client side of the house, with warnings about the scheduled support phase-out for Windows XP, Microsoft officials are beginning to do the same with Windows Server.

In a September 15 blog post to the Windows Server Division Weblog, Microsoft officials provided an early warnings about the approaching end-of-support dates for customers running Windows Server 2000 and 2003 .

Microsoft provides support — “mainstream,” followed by “extended” — for most of its business software for ten years. The main difference between mainstream and extended support is the way Microsoft treats non-security-specific hotfixes. Under mainstream support, Microsoft provides these kinds of hotfixes for free.

Under extended, customers are required to pay for non-security hotfixes and must sign an extended hotfix agreement, purchased within 90 days of mainstream support ending. (Or, if customers are covered by Software Assurance, the extended hotfix agreement can be purchased at any time.)

This week, Microsoft noted that extended Support for Windows 2000 Server will end on July 13, 2010. That means, at that time, “Windows 2000 Server will no longer be publicly supported,” but customers will be able to continue to get Self-Help Online Support.

(”Self-Help Online Support” means online access to Knowledge Base articles, FAQs, troubleshooting tools. This type of support is available for a Microsoft product’s entire lifecycle, plus a mnimum of 12 months after a product reaches its end of support phase.)

Also on July 13, 2010, Windows Server 2003 and Windows Server 2003 R2 will move from the mainstream support to the extended support phase. Microsoft will offer customers free security updates and paid support for those releases. It also means, according to the September 15 blog post, that “non-security hotfixes developed during the Extended Support phase will be provided ONLY to customers who enroll in Extended Hotfix Support (EHS).”

Microsoft also put to rest talk that the company might be issuing a third service pack for Windows Server 2003. No such Service Pack is coming, according to the blog post.