These are 1600 x 1200 pixel wallpapers from Harry Potter 7, the Deathly Hallows Part 2. They have been slightly customized from promotional graphics widely available to have more punch in their colours and annoying logos removed.
Please click on the wallpaper you want to view, then right click after it loads at full size if you want to download it (PC instructions, not sure what you do for Mac).
If you’re using Windows XP, you can learn how to create your own customized Windows XP screen saver with instructions via this link.
I also have instructions for how to use Windows 7′s nice rotating background feature to rotate many of these wallpapers on your computer if you didn’t know how to enable it.