http://microsoft.com/technet/treeview/default.asp?url=/technet/subscriptions/cdsampler.asp

get this technet cd, it is free, no s/h charge either. It contains
• Updated Service Packs for Windows® 2000 and Windows® XP
• Security patches for Windows® 2000 Server and Windows® 98
• Resource Kits
• Deployment and planning guides
• White papers

Now you don't have to download the service packs, and security patches again when formating your computer!