Microsoft has stopped its support for Windows Server 2000 and cut back on support for its Windows Server 2003.
All public support for the server operating system ended on Tuesday, Microsoft said on its help and support page. Windows Server 2000 customers will only have access to self-help online support, including access to FAQs and community support forums.
In addition, the company took Windows Server 2003 off mainstream support, but customers will continue to receive security updates and access to paid support for the software until 2015.
However, specific patches called hotfixes are now only available to customers who purchase Extended Hotfix Support. The company will not make any design changes or feature requests, according to Microsoft's support lifecycle policy FAQ page.
The upgrade from Windows Server 2003 to a later version of the software such as Windows Server 2008 could be costly, according to research company eDigitalResearch.
"It's not the licence costs, it's the act of managing the transition to a different server setup," Shane Wright, technical director of eDigitalResearch, told ZDNet UK on Tuesday.
Costs could include running test servers, certification, regression, performance and compatibility testing, Wright said.
"Desktops can be upgraded piecemeal... the server infrastructure is often all or nothing — especially if any new features are to be taken advantage of," he said. "It's a necessary process."