Ok, so I believe I have everything installed as it should be, and nothing broke when I changed my XF86Config file to have Driver "nvidia" and Load "glx" in it (in their respective places of course). But, it doesn't appear that anything is being hardware accelerated. None of the 3D screensavers run at anywhere near hardware accelerated speeds.
Any ideas would be much appreciated :-)
PS. I've got an NVidia TNT2 video card.