Sounds as if you're confusing one of the DesktopX (??????) themes with the AquaReal, Marine Aquarium 2, SimAquarium or Digital Minds 'Aquarium' screensavers .... all of which are pretty resource hungry.
If your card doesn't have 3D support you would have hassles with the savers, never mind the aggro without accelerated 3D support!

Can't answer for the specific D/L you mention but one of the admins might be able to help.
Certainly the lack of a punchy card would screw up the screenies performance.