I'm a little late to notice this, but Eilene Hao, a PM on the SharePoint Workflow team, has put together a massive 7 part series on writing workflows in SharePoint. I haven't focused a lot on workflows inside of Office, looks like I need to spin up a VPC and dive through some articles!
I try to start the Workflow Designer within SharePoint Designer 2007; I can get it to pull up, but then when I attempt to add anything (condition, action, etc) and the dialog box will pop up for a split second and close on its own. Why would this do this? I have done this over and over and receive the same results and am not able to use this. Is there some sort of add-on that I'm missing or a program that I'm possibly using that would cause this?