You created a really great demo for a client. Now, if you could just remember where you put it. You checked the My Documents folder, but it didn't jump out at you.
Create a folder structure that tells you who the presentation was created for, what the presentation is about and maybe even when you made it. Create new folders when you start a new project.
Most people like to store things in the My Documents folder. That is fine. Just create the working structure inside the My Documents folder.
In my main folder, I have a folder for each client I have worked with. Inside those folders, I have separate folders for each project or revision of a project I worked on.
For example, the content for this book is all in one folder. Inside that folder are folders for each of the presentations I used to create the screen shots for each chapter. There are also folders for any correspondence about the book and a folder for the PDFs as they were sent out for review. The whole structure not only makes it easier to find the things I create, it ensures I put all my linked files for a particular presentation in the same folder as that presentation.