Many clients have asked for references for not just a technical training but power user training and references for MOSS. This should compliment an earlier recommendation for technical references and training. I recommend picking up a copy of SharePoint 2007 User's Guide: Learning Microsoft's Collaboration and Productivity Platform by Seth Bates and Tony Smith.
This series so far has been really good for SharePoint 2007. The book lays out step by step instructions on how to do things. If you would like to read an introductory chapter please go here.
I would also highly recommend using the Office SharePoint 2007 Help and How to Site as there is a top of information here with steps on how to do every day sorts of things.
As for training I am going to again refer to MindSharp as they offer a SharePoint 2007 Power Users Course.