Recently came across these excellent tutorial websites. The first one is for all things pertaining to AT. Click here to access this and then check out the main library. There are all kinds of training materials for AT and special education resources.
The second site was developed by Tammy Worcester. Click here to access detailed, yet concise handouts on PowerPoint basics for the Mac or Windows. Click on "Handouts/Presentations" and then scroll down to PPT Basics.