Windows has some very cool wallpapers available in it. Here are a few old favorites from old and new versions of Windows. These could be interesting choices for a Windows lookalike desktop on Cinnamon or KDE. These are very cool, especially the high-res wallpapers for Windows 10.
Complete pack of Windows wallpapers from every release of Windows, even hidden and promotional wallpapers. I previously had linked to a forum post that had this file, now it has 404 post not found. So I uploaded it to Google drive. This is a cool pack to have on your computer to brighten up your Linux desktop environment.
https://drive.google.com/open?id=0B-W1m-kHGr03RVJ4ZjU3dnRHVjg. 506 megabytes.
Download Windows 7 Wallpapers Pack (RTM Build 7600.16385).
Here are some cool Windows wallpapers, these are perfect for a Linux based pretend Windows desktop.
Windows `98 loading screen wallpaper: http://fc09.deviantart.net/fs71/f/2011/209/a/2/large_windows_98_wallpaper_by_jlsgraphics-d41y8cx.jpg.
The Windows `95 setup wallpaper: http://www.securitronlinux.com/wp-content/uploads/2013/05/windows-98-setup.png.
super-high resolution bliss wallpaper: http://i.imgur.com/UwuqHf6.jpg.
Microsoft featured wallpapers. The latest featured wallpapers on the Microsoft website. A nice place to go and get some free wallpapers.
https://support.microsoft.com/en-us/help/17780/featured-wallpapers.