Win98 Service Pack: "UNOFFICIAL Windows98 Second Edition Service Pack 1.1 (Freeware)

Microsoft has never released a service pack for Windows98 SE. But I made a Service Pack for Windows98 SE users. It contains all Windows98 SE updates from Windows Update site and more."

Also includes Defrag and Scandisk from Windows ME - which are way quicker than the Win98 one. Don't know how legal this is, but the defrag really is way quicker.