If you have a digital camera,any picture you take can be used as a screen saver WITHOUT RESIZING.Just upload the pictures onto your computer,find the one you want,right click on your mouse and go to "set as desktop wallpaper".ALL computers have this option and you DONT need to resize the picture because the computer does this by its self.
Make sure the picture is horizontal though so that it covers the whole screen
I just take pretty pitures of my girls and do what Iv just told you..I change mine every couple of days