whats is mesa
 

whats is mesa and how do i switch to my installed graphics card?

mesaGL is a 100% software based implementation of OpenGL, for graphics cards with no capabilites to support any of it in hardware. I don't see what you mean by the second part of your question though.

i have a nv18 geforce 4 mx400 agp how do i enable the support from the hardware?

Nvidia has great Linux driver support. Download the latest version from here: http://www.nvidia.com/object/unix.html
Then, follow their instructions, which basically involves going to init 3, running their installer (which puts Nvidia as a kernel module), and changing the driver in your /etc/X11/xorg.conf from "nv" to "nvidia".
Or, if you don't like binary drivers, you can try the MESA route, in which case I have no advice to offer :)

when i go to install NVIDIA-Linux-x86-1.0-8178-pkg1.run
i get this error message during insallation

error-unable to find the kernal source tree for the current running kernel,please make sure you have installerd the kernel source file for your kernel and that they are properly configured,if you know where the correct kernel key source file are installed you may specify the kernel source path with the `-kernel-source-path command line option



what do i do?

As the message says it very clear that you do not have the kernel-source package installed. You will have to install the kernel-source-<version>mdk.rpm from your distro CDs. After installing the rpm you will have to compile it and then go run the nvidia installer.

in what directory are the kernel-source package on my disro i am using mandrake 1.01 on dvd
and how do i compile it?