Just when I wanted to begin with defining a custom workflow, Joris posted a nice introduction with very useful links! God bless those belgians :)

A good starting point is the white paper – Walkthrough : Creating Office SharePoint Server 2007 workflows with Visual Studio but there are still some things you should really now before starting developing your own workflows on top of the SharePoint 2007 platform. This is the first of a series of postings about workflow in SharePoint 2007. InfoPath 2007 is used in a couple of places in a SharePoint driven workflow: In the workflow initiation and association forms which are used to set workflow parameters before a workflow starts In a workflow modification form which enables users to alter the workflow while it is running In the workflow task forms which is opened when a user clicks the task link which is assigned within the workflow process. When you want to develop a SharePoint workflow with Visual Studio 2005 you will first need to install the SharePoint workflow project templates. These Visual Studio project templates are installed when you install either the ECM Starter Kit (for Microsoft Office SharePoint Server ) or the Workflow Developer Starter Kit for Windows SharePoint Services 3.0... Read more @ JOPX blog