The very most basic changes to the background and color scheme are done through themes. You can do an internet search for .TSK files and find a large variety to suit your tastes. You copy the TSK file to your "My Documents" folder and then click
Start,
Settings,
Personal,
Today and then select the TSK file from the list on the
Appearance tab.
As a very very very basic selection, you can try looking at Microsoft's own theme collection to get you started.
http://www.microsoft.com/windowsmobi...ds/themes.mspx