The background of the folder means the white space that appears when you open MY Computer or the document folder, where you scroll through the list of icons and files that are inside.

This background of every single folder can be changed with several small tools but, recently, it came out on the DeviantArt graphics site, a very small program that applies a change to the folder options tab.
Without leaving any software in the background, without unnecessary consumption of memory and above all, without compromising the stability of the system, you can, only for Windows 7, download AveFolderBG that adds the option to change the background, directly in the folder properties.
The integration in the Windows shell (in its interface) makes this operation much more convenient, faster and without installing extra programs.In fact, this Avefolder is not a software to install but a file package that includes a dll and two modified registry keys.
To make the folder background change option appear, you must then download AveFolderBG, unpack it and install it by running the install.bat file as administrator.
After giving the ok to copy the file and modifying the registry, you must log off the Windows user or restart the computer to apply the changes.

Now you can open the resource explorer, open a folder that you want to see another background, such as the one with the music, right click on the empty white space, press “Properties” and find that, among the tabs, there is a new one called “Folder Background“. An image to be used as background for that folder, you can change the color of the text under the icons even with a shadow effect and you can apply these graphic changes to all the subfolders of that.

The image chosen, if small, will be seen side by side, while if it is large, it will be central, in its original size.
The Avefolder background change supports only photos and images from the Jpg or Jpeg format.
If you only want to change color, you need to load a very small image made of a uniform color.
You can put a different background for each folder on your computer if you wanted to.

To remove the Folder Background tab from the properties of the folders and return to the previous situation, simply run the Uninstall.bat file and all these options vanish.

AveFolder can be downloaded for Windows 7 on the Deviantart website.

I have not tried but for Windows Vista it should be the same AveFolder downloadable from here.

For Windows XP the change of the background in the folders you can certainly do with a program like Custom Folder (look for the word Download in the page that opens) or with WindowPaperXP