Well, first of all, some distros can install nvidia-drivers with a packagemanager. That is very distro-spesific, so there isn't a universal howto there.
Anyways, this is how I do with slackware.
If you are going to use 64bit driver or 32bit doesn't depend on the cpu, but if your using a x86_64 OS or regular x86. Eitherway
http://www.nvidia.com/Download/index.aspx?lang=en-us and download your preferred choice (32/64bit).
Put it somewhere nice, and log off and shutdown you X. If you have trouble to exit the kdm/gdm or any other graphics the howto i think says to change to runlevel 1. I never do this.
Log in (With console, not graphicly) as root, and cd to the directory where you downloaded your file.
Simply do:
sh ./NVIDIA-Linux-x86_64-100.14.19-pkg2.run (64bits)
or
sh ./NVIDIA-Linux-x86-100.14.19-pkg1.run (32bits)
The installer will do the rest. It will update your configfiles to use the nvidiadriver as well.
If you didn't shut down gdm/kdm/xdm, restart it by pressing ctrl+alt+backspace
Remember to take a backup of /etc/X11/xorg.conf
This is really important incase things screw up.
Edit:
You might have to
chmod +x your_nvidia_driver_here
to make it executable.
