because there are so many awesome wallpapers here, and i would hate to force u to only get to use one, i give u the automatic wallpaper changer.
all u have to do is make a folder to save all your wallpapers in and then set this program to take pics from that folder. then u can set the program to change the background as often as 5 minutes, to as little as once every year. anything in between that u can do.
all u have to do is download this program and install it. then u are set to go. its totaly free and completely safe.
http://awc.smurphy.co.uk/