The official One Tree Hill website has a Sims 3 section in which they offer 10 wallpapers (they are a bit blurry though and make horrible wallpapers) as well as 5 screensavers.  You can either download them from the official Sims 3 One Tree Hill site or from my Flickr gallery.  They are offered in 800×600, 1024×768 and 1280×1024 sizes.

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