Well i have several themes i use. My fav has to be the Sexy XP theme.
WinCustomize: Sexy for XP by vStyler for WindowBlinds
As for wallpaper. I use several thousand wallpapers. I change them like daily. So i dont really have a favorite. I have several skins from Deviatnart and more from wincustomize.
what program can change your wallpaper daily besides webshots