Are you worrying ....why your XP desktop icons have a background color. Here is the process to restore it back by checking / un checking the checkbox list items.
Usually the look of normal desktop and the desktop icons with color desktop as shown below.
1 - Right click on My Computer
2 - Go to properties
3 - Click on Advanced tab
4 - Now under Performances column - click on Settings
5 - You will get the list of checkbox items as below
6 - Now check "Use drop shadows for icon labels on the desktop" check box - If it is already ticked please un-tick it else tick it.
7 - Even though if it is not worked out - then check "Use a background image for each folder type" it is already ticked please un-tick it else tick it.
Way - II
8 - In other way, first you can check with Right click on Desktop and "Arrange Icons By" -> untick the "Lock WebItems on Desktop"