[CentOS] Installing nVidia driver on remote CentOS 4

Hi,
There's a linux cluster somewhere (using Rocks), and I use remote
desktop (nxmachine) to do the work on the frontend of the cluster. The
desktop is Gnome. And, I intend to install new nVidia driver, but it
requires me to stop the X Server. I check around the internet, they say
we can use the /etc/init.d/gdm stop, but I can't run it since the gdm
file does not exist. Another alternative is by rebooting the Linux (of
course, we change the inittab before). But I don't know how to reboot
remotely. Moreover, I don't know if it is safe to reboot Linux remotely, because I
can't physically access the linux workstation. Oh, the operating
system of the Linux is CentOS 4. 
What should I do ?
Thanks.


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