According to recent research by Ben Edelman and Hannah Rosenbaum, the most dangerous websites to visit are those advertising free screensavers. 64% of sites advertising free screensavers caused problems for their users by installing spyware or adware or by sending spam. I repeat: 64%! Your computer may even be hijacked to enable spam to be sent through it, making it appear as though you're the villain sending the spam! It is much safer to download a graphic for wallpaper and to stick with one of the screensavers that come with your machine. If you must have a flashy screensaver, the BBC Science & Nature pages offer excellent wildlife screensavers that I know are safe. If you want a monthly nature wallpaper with a calendar, visit the UK Phenology Network. For art wallpapers (sample shown) visit Coxsoft Art. If you have XnView, load your favourite graphic, click "Tools", then "Set as wallpaper"; it does it for you.