SharePoint Workflow Articles
David Mann, the author of Workflow in the 2007 Microsoft Office System, has recently published two articles on MSDN, titles and links provided below. For those just getting started with creating their own custom workflows, David's book is a great introduction to the subject. The articles cover the creation of workflow components using Visual Studio and SharePoint Designer as well as the difference between the approaches. If your one that prefers articles over books, these 2 articles are worth reading. If you have already read his book, the articles will be of minimal value in terms of new content but could serve as a refresher.