Fork bombing a Linux machine as a non-root user

[M.Rudra]

Hello All,

When my Windows system crashed recently, a patient of mine introduced
me to Linux as a secure OS but today I read an article on fork bombing
a Linux system.

http://www.securityfocus.com/columnists/308?ref=rssdebia

As a non-geek user I am concerned as I thought Linux is very secure. 
So I googled "fork bombing" and after reading them, I have some doubts :

1] Is this applicable to newer version of FC3/4 or will this affect
older stable versions too.
2] The article mentions Debian survived among others but some of the
Linux distributions are  vulnerable to fork bombing. Is FC a part of
the latter ?
3] If a non -root 'user' can bring down the system, then can a person
without login facility bring down the system too if the machine is
connected to the Internet ?.
4] What precautions must one take for [a] general PC [b] servers. do
they differ ?
5] Does one have to download a patch for the kernel ? If we install an
older stable version of the distro  will the system be safe from such
an attack ?

All comments and pointers to online resources are welcome.
Thanks for reading. 
-- 
MR