Change the Background in WMP12

Step 1:

Click Start button, type "regedit" (without quotes), the program will appear at the top of the list; right click over it and select run as Admin ; accept any security prompt.

Step 2:

Go to HKEY_CURRENT_USER\Software\Microsoft\MediaPlayer\Preferences in the left side pane

 

Step 3:

In the right hand pane look for "LibraryBackgroundImage"  double click on it.  Make sure that hexadecimal is checked and enter a number from 0 to 6 in the value data field and click OK

Default is 6

change the value from 6 to your wish (6 to 0)

Here I have changed to 3 the result is