Set Folder Icon for all Os

You have to create a autorun.inf file in the root of the hard drive.

[autorun]
icon=path\to\icon.ico

For example, if your drive is E:\ and your icon is at E:\icons\myicon.ico, you would create a file in notepad that looks like this:

[autorun]
icon=icons\myicon.ico

And save it as E:\autorun.inf. (Remember to select All Files in the Save As dialog.)

The icon file has to be on the drive, so that it can be transferred between other computers along with the drive.