This is approximately how the screensaver will look on a Mac and PC. The transitions, speed etc will vary according to the options you have set and the graphics card in your computer.
The free download is a folder containing jpeg images, it does not contain any programs.

Once downloaded save the folder 'Oxford' to your hard drive.
PC:- In your screensaver settings. browse to and select the 'Oxford' folder, make any other settings and press test or preview.
Mac:- Go to System Preferences, Desktop and Screensaver. Chose Screensaver tab, click Choose Folder, browse to and select the 'Oxford' folder. Set any options and press test.