You can turn on check boxes in Windows 7. This can be useful if you would like to delete or move a group of folders/files.
To categorize e-mails it is easiest to add a new button to your Quick Access Toolbar. This video will show you what button to add and how to use it to assign a category to your e-mails.
Using the keyboard to navigate folders and files will save you time. It's much faster then visually searching for a folder and using your mouse.
Utilizing the "Favorites" toolbar in Windows 7 will allow you easier and quicker access to folders and files. This video is specific to Windows 7.
The Quick Launch Toolbar can be a great tool for quick access to your most used programs.