Originally Posted by yxwq
I'm a newbie
As others explained, you almost certainly shouldn't want an obsolete version of RedHat.
So if you had a valid reason to want something in the Red Hat family, but want something free, then look at Centos or Fedora.
But more likely, you don't even have a valid reason for wanting Linux in the Red Hat family. The fact that you asked about redhat 9.0 doesn't imply good things about the quality of info you have so far for your decision. There's nothing wrong with not knowing such things. You said yourself you're a newbie.
The whole Red Hat family within Linux is not very good for newbies. You would be better off with Ubuntu (which is in the Debian family of Linux distributions).
I used to recommend Mepis, which I use myself at home, because I think KDE was
much more beginner friendly than Gnome. Mepis is quite similar to Ubuntu but has KDE as the default desktop rather than Gnome (Mepis also has a few other details more beginner friendly than Ubuntu).
But the beginner friendly KDE has been replaced by KDE 4, which is not at all beginner friendly. If you want KDE 4, I think Mepis is a much better choice than KUbuntu (the KDE option based on Ubuntu). But I think KDE 4 is flawed enough that Gnome is better. I still use the older KDE myself.
You can switch almost any Linux distribution to almost any desktop. But a beginner is much better off selecting a distribution and desktop together and sticking with the desktop that is the focus of support for that distribution.