As a web designer, I have to open up multiple verisons of Windows running various web browsers and versions of each. To do this, I've found that VMWare Fusion works great. I can run most any operating system right on my Mac without needing multiple computers on my desk. To keep things tidy, I put together some consistent desktop wallpapers for each operating system that matches the OS branding colors. Most Windows primary color is blue, but they each have their own unique hue that sets them apart from the others.
If you have a similar setup, or just want some super-simple desktop wallpaper to remind you which version of Windows you're looking at, feel free to download them from the links below.
VMWare Desktop Wallpaper
All images are 1920x1080 in high quality PNG format, perfect for any VM you might want to run. Hope you find these useful.