Add Falling Snow To Your Windows Desktop [1]
In many parts of the world, Christmas is a time for snow. Hence the many websites which roll out the Javascript at this time of year, in order to have a gentle flurry of snowflakes drifting down the screen.
If you're not fed up with the effect yet, and you'd actually like snowflakes on your Windows PC, all you need is a small free Windows program called Desktop Snow OK. The download is less than 0.1 MB, it's trustworthy according to VirusTotal and Web of Trust, and it works on all recent versions of Windows (including 8). You can get it from http://www.softwareok.com/?Download=DesktopSnowOK [3] by clicking on one of the 2 blue links (to select whether you want the 32- or 64-bit version).
Avoid clicking the large green Download button - it's merely an advert for another program entirely.
As you can see from the config screen shot below, the program is pretty flexible. In addition to changing the speed and design of the snowflakes, you can also automatically hide them for a specific number of seconds when you press a key or move the mouse, so they don't interfere with your work.

