Windows 7 comes with enough screensavers installed by default to get the job done. In fact, with modern LCD monitors and standard power saving features, screensavers are unnecessary in almost all situations. They don't count as an advanced Windows 7 feature, but, what is necessary never trumps tricking out your computer for maximum fun. These Top 10 Windows 7 Screensavers bring the fun before your monitor decides it has had enough and powers down into sleep mode.
You can find most of these screensavers at your favorite software download website. Consider cnet's download.com screensaver listing if you don't have one.