Please help, I'm out of options (GLX errors)

[Senectus .]

For over 8 hours now I've been banging my head against this bloody PC.
I can't find ANYTHING that makes a difference, all the scouring of the
nvidia forums, the ubuntu forums the mail list archives.. I've tried
all sorts of things, new kernel, symbolic links to modules,
reinstalling packages.
I even asked for help for hour in IRC with no results. (managed to fix
someone else's though :-P )
I'm running hoary, with the k7 kernel and a nvidia 5600 (NV31) card.
If I try to run anything 3d I get this
$ glxgears
Xlib:  extension "GLX" missing on display ":0.0".
glxgears: Error: couldn't get an RGB, Double-buffered visual.

Screen savers (GL ones) don't work as well.

Can anyone suggest anything at all to help me fix this thing?
-- 
Ubuntu Hoary 5.04 
"The thing Ubuntu means to me is, I'm glad I didn't get a Debian
Tattoo..." - Matthew Lambie