I'm planning to provide training for 500 sales people on Office 2007 early '08. Please share your thoughts based on your experiences deploying office 200X training...what worked well and what did not work well? Any trianing materials and references that you found worked extremely well? Can users handle the upgrade with a only a "Quick Ref" guide?

Going back to the basics with the WIIFM principle here.

Used many generic (pre-canned) Office (or other suite) training tools. Most are OK, but "just OK" at best.

For best results, concrete examples of performing the tasks they generally perform will have the most "stickiness" and relevance. It is also a good way to deploy new templates, standards and reinforce some expectations.

If you're still working on Office 2007 training, check out officetestprep.com

They offer online self-paced courses specifically for training in Office 2007.