Wicked! Thanks for the help ...
I am laughing at myself, but you know, I wasted like ... 5 hours trying to figure this damn thing out, and it was my own freaking stupidity that caused all the trouble.
I didn't know about the SU thing though.
In short, here is my solution ... in case any one else is having any difficulty.
In order to install the nVidia driver which is a RUN file, you have to have the Kernel source installed. And, as most people would know (all except me anyway), you can install it by sticking one of your Mandrake CDs into the drive, going to [System/Configuration/configure computer], clicking on Software management and surfing the list of available install packages until you find the appropriate kernel. It automatically installs anything else you need.
Then (assuming you have downloaded the run file), you disable graphical user interface (dunno if this is totally necessary, but it worked so thats all that counts) [system/configuration/configure computer/boot/auto login] and DE-SELECT 'launch graphical environment'.
Then type SU at the command prompt (I assume this is to switch to 'single user' mode, which I assume grants the user nearly all required ROOT permissions.
Then follow the rest of the nVidia installer information.
Feel free to contact me if you want any more input. We NewBs need to stick together (heheh)