The update rollup, which replaces Windows 2000 SP5 (Service Pack 5), ships as a high-priority update on the Windows Update site, where it will be listed in the "Critical and Service Packs" category.
In a security advisory posted Tuesday, Microsoft Corp. said the rollup is applicable to Windows 2000 client and server releases and requires the prior installation of SP4.
"[It] contains additional important fixes in files that have not previously been part of individual security updates [and] additional enhancements that increase system security, reliability, reduce support costs and support the current generation of PC hardware," the company said.
But the company said the rollup initially will not be distributed over Automatic Updates because Windows 2000 customers are being transitioned to a new version of Windows Update. "Once the transition is complete, which is expected in early July, Automatic Updates will be enabled for the update rollup."
Microsoft said the rollup contains all security updates produced for Windows 2000 between the time SP4 was released and April 30, 2005, the time when the code was "locked down for final testing."
Windows 2000 remains the most dominant operating system used in the enterprise, but once mainstream support ends June 30, analysts expect corporate migration to Windows XP to speed up.
Microsoft divides its support life cycle into two phases: mainstream and extended. Once a product enters the extended support period, Microsoft charges for support.
But the company still will provide Windows 2000 security patches for free through June 10, 2010.
Microsoft has posted a Knowledge Base article that describes the contents of the Windows 2000 update rollup.