Re: FSAA with GeForce4 MX 4000?
Correct, GLX extensions are only around when they are in the 'GLX extensions list' (officially that is the case when an extension is in both the client and server GLX list).
There are a number of forms of 'jaggies' removal. Multisampling is one of the algorithms to do it (rendering an image at a much higher resolution and then basically downscaling it). I'm not sure what the difference between all the algorithms is and why it isn't offered on the geforce4mx in opengl. Most likely the hardware doesn't support (or in a limited fashion) or even handled in software.
You can also enable fsaa from within your program using the nv-control api which is part of nvidia-settings. Note that you then need to set it before you initialize opengl.