The Office Online site also has a bunch of demos and training to help people move from Office 2003 and 2007.

Here are few links that may be helpful to learn about changes between Office 2003 and Office 2007:

There are also app-specific “What’s New” Help topics – here are a few:

Also, there are app-specific (free) training courses: http://office.microsoft.com/en-us/training/HA102255331033.aspx