LabMice.net have put together some great resource centres to help get the most out of your O/S

Windows 2000 Service Pack 3 has been officially released and is a recommended upgrade according to Microsoft. It includes a collection of fixes in the following areas: application compatibility, operating system reliability, security, and setup. Windows 2000 SP3 includes the updates contained in Windows 2000 Service Pack 1 (SP1), Windows 2000 Service Pack 2 (SP2) and Windows 2000 Security Rollup Package 1.

Heres a good resource site for the new SP, should help you with any queries or SP issues

Windows 2000 SP3 Resource Centre:

heres one for those running XP

Windows XP Resource Centre: