I use Premiere Elements 3.0. I’ve created many projects to edit footage from my DV camera. I just discovered that PE creates cached media files, autosaves and other files that take up a lot of space! Incredibly, PE doesn’t give you a way to delete projects you have saved so these extra files accumulate on your hard drive. I found this thread on how to delete a Premier Elements project.
You go to where your project files are being saved and delete the folders:
Adobe Premiere Elements AutoSave
Adobe Premiere Elements Preview Files
Media Cache Files