No need to beg borrow or steal Microsoft provide free training:
There are also some really useful interactive guides on the MS website where users can navigate to a certain menu/button/function in a virtual 2003 environment. The tool will then show them how to complete the same action in 2010. I found these invaluable when we made the switch...
http://office.microsoft.com/en-us/support/learn-where-menu-and-tool... also looks like a useful tool - if Kyla hadn't pipped me to the post!
Another vote for the inteactive guides mentioned. Very useful migration tool.
I can heartily endorse the interactive guides already recommended. You find the challenge is with "power" users who often get the hump with the ribbons wheras ordinary/novice users usually find ribbons easier. The bit to focus on is the File menu/tab, which can be a bit traumatic for newbies.