Microsoft has a vast knowledge base available for all of their products.
For 40 years, Computerworld has been the leading source of technology news and information for IT influencers worldwide. Computerworld's award-winning Web site (Computerworld.com), weekly publication, focused conference series and custom research form the hub of the world's largest global IT media network.
How Stuff Works - PC
Learn all about how your personal computer works at How Stuff Works.
WhatIs.com« is a knowledge exploration and self-education tool about information technology, especially about the Internet and computers. It contains over 4,500 individual encyclopedic definition/topics, a number of "Fast Reference" pages and learning tools. The topics contain about 12,000 hyperlinked cross-references between definition-topics and to other sites for further information. The site is constantly updated.
Dell provides support and downloads for all of their products through this site.