Screen Savers: Windows .scr In Ubuntu?
Many Windows screensavers can be run in Wine.
Assuming your screensaver is stored in your Downloads folder, just run wine ~\Downloads\startrekscreensaver.scr /s in your Terminal.
Windows screensavers have not been integrated into Linux so you won't be able to easily set them as your screensaver.
You could also try installing xscreensaver-gl-extra for more screensaver choices. Many of these screensavers come with configuration options that can be modified with the default gnome-screensaver; you will need you to install xscreensaver to change those options.