Wendy,
I agree, many times all of the bells and whistles get in the way and actually distract from the message. The Microsoft videos on practicing restraint with PowerPoint mentioned in this course are a great resource for students and educators alike when developing presentations. I suggest sharing the link with students, this may help with transition overkill.
Here is link to the Microsoft website, providing a basic overview of how to create a PowerPoint presentation- it is great for beginners:
http://office.microsoft.com/en-us/powerpoint-help/create-your-first-presentation-RZ001129842.aspx
Wishing you continued success in the classroom.
Theresa Schmitt