I don't recall the screen saver in question, so not entirely certain.Uhm... so then how was this running fine in Win98, five years ago...?
Probably it wasn't 3d accelerated. The desktop could be a static image in memory; a snapshot of the desktop when the screensaver started. (unlike our galaxy map, which changes -and- is generated on the video card) The glass ball distorts a rectangle of the static image, blits the static image and the small glass ball distortioned rectangle directly to video memory. (but not to texture memory on the video card.)