How can I customise Windows 2000 Prof. d

I have setup a Backup user logon on a PC running Windows 2000 professional. I want to change the wallpaper on this logon account, and add/delete some desktop icons. Whenever I log off and log on again, any changes I’ve made have disappeared! How do I stop this happening? I’ve tried temporarily adding this user to the Power Users group, but that didn’t work either!