IBM developerWorks has posted a fantastic nine-part guide for transitioning from a Windows to a Linux environment.
This roadmap is designed to help you take the experience and knowledge that you already have in computing and redirect it to working in Linux. It's not the only reference you'll ever need, but it will help you get past some of your first obstacles and adjust to a new and, I think, exciting approach to computing. As you follow this roadmap, you'll discover many new resources to help you learn, troubleshoot, and manage Linux.
Note that this guide is geared towards helping you apply your knowledge of a Windows environment to Linux, rather than guiding you through the Linux installation/migration process itself.