Microsoft had originally intended to release a fifth service pack for Windows 2000, but eventually canceled it, and instead released the Update Rollup 1 for Windows 2000 Service Pack 4 in 2005, which is a collection of all the security-related hotfixes and some other significant issues.

The collection replaces what would have been the fifth service pack for the operating system, which was released in March 2000. "Because Microsoft believes the Update Rollup will meet the needs of customers better than a new service pack, there will be no Service Pack 5 (SP5) for Windows 2000," the software maker said.