It doesn't matter where you place the file as long as you know the path to the file. The root account has access to every file at all times. I download all of my files to my user's account (/home/sn/stuff) and I just use the command line to copy files where I need them. I place all source tarballs in /usr/src so whenever I need to upgrade my kernel, I don't have to search everywhere for the nforce ethernet source.
Now, my directions were assuming that you logged in as root or used su - and you were using the command line. I don't like using a lot of GUIs to get my work done. They can be too buggy sometimes.
Now, I use KDE and I am going to type these instructions from using KDE, but you can adapt them to Gnome or whatever window manager you happen to use.
1 - Download http://download.nvidia.com/XFree86/n....0-0261.tar.gz
somewhere as your regular user (/home/user)
2 - Open a command line (konsole in KDE)
3 - change directories to where you downloaded the file (if necessary)
4 - tar xzvf NVIDIA_nforce-1.0-0261.tar.gz
5 - cd nforce
6 - make
7 - su
8 - enter root's password
9 - make install (no error messages should be generated)
10 - /sbin/lsmod | grep nvnet (check to make sure nvnet was added to the kernel
11 - /sbin/modprobe nvnet if no response is generated
12 - less /etc/modules.conf to check that the alias was set up properly for nvnet (alias eth0 nvnet)
13 - setup your network card (run neat. you will need to enter root's password)
I know that this might be a little long, but I wanted to make sure you got enough detail to help out. If you still need help, let me know.