http://www.door2windows.com/windows-7-user-picture-frame-changer-change-your-user-picture-frame-with-one-click/

to change the frame.

-or-

to remove the startmenu pic.

http://www.door2windows.com/windows-7-start-menu-user-picture-remover-remove-windows-7-start-menu-user-picture-with-one-click/