This is much like the lessons you learn in life. Ultimately, you are responsible for your own direction in life.

Other's are there to lend you their experiences. They will all offer you advise that has worked for them. It's neither right or wrong, it is simply their experience. Your job in life is to experience as much diversity as you can handle to learn your own truths and establish your own path to enlightenment.

The journey is a long one and you will make small corrections to your course before you reach your ultimate destiny with (WARNING: SPOILER AHEAD) Fedora/RHEL/CentOS. haha just kidding. Just have fun with it bro.

Ok then shall i work for a distribution that gave me certification or a distribution that i love??
but i didn't try any thing yet
I had only seen my friends working on different dist may be others working on BSD or Solaris
I think the way is not easy
I started to go to a Linux courses it costs much put i really want to learn
Then the question will be as follows
How can i choose my dist.???

You answered your question in the first sentance of your last post.

Do you want to be certified? Then look at distro's that offer certification. Do you love a particular one? How do you know you love someone unless you spend a lot of time with them?

I'm sure someone has already offered this link to you, but here it is again:
http://distrowatch.com/dwres.php?resource=major

Stick with a major distro so you will have plenty of support options. Read the descriptions and history of each distro and decide what best fits your motives and aspirations.

1) Download it
2) Install it
3) Profit

Thank you all for the help you gave to me
Ok,lets talk what will happen if i choosed a certain dist. (Lets assume Debian)
Will the programs that work on different dist. will work with me?
Is the support of Debian good??
can i take a driver that works on different dist and make it work for me?
I think if all answers are yes then what is the main difference between dist.
If no then choosing a specific dist will be hard to be achieved

generally, yes. For instance, truecrypt is officially precompiled for you but only as a debian package. But to use it on Fedora, I simply unpack the debian files and run the truecrypt executable and it works perfectly. Different applications may or may not work so easily.

Support for debian is great - any of the major distributions will have lots of pre-compiled applications in their repositories to get you started.

You will always be able to compile from source code but depending on the complexity and age of the source, you may need to do a bit of googling to get something working due to incompatible libraries and file locations ,etc.

if there is incompatible libraries can this problem be solved??
and this a big problem for me :
How old are those packages?

I'm getting out of my realm of expertise here but the library issue is generally fixed by googling any error messages you find and then installing an updated version of some RPM, or extracting the library from the archive and dropping int into a lib folder.

And it just depends on what application you're talking about... Linux is just a kernel and each distribution takes that kernel and develops the rest of the OS into their own creation. The distro developers choose to include different packages by default, and make their own improvements to the OS based on their own philosophies and objectives. That's how you end up with purpose specific distros dedicated to specific tasks or functions like engineering, Linux Noobz, forensics, firewalls, incident handling, etc.

Thanks all
Now i think i need a certification to help me to have work i think redhat certification will be very good at this time
But what shall i use Fedora or Centos or Redhat??

if you're mostly going to be doing server related stuff, then I'd go with CentOS because the versions don't come out quite as often and it's based directly off RHEL so it's very stable.

If you're mostly doing desktop work, then go with Fedora. They release a new version about every 18 months so you get a chance to re-install it more often and "refresh" your skills and get a healthy lesson on backups and restores of your personal information across upgrades. Plus, from what I've seen, Fedora (vs CentOS) has a lot more experimental and cutting edge applications included in the distro. More eye candy and fun things to play with.

khodeir,
I'm new to linux too, and I suggest you to try Slackware.
"Oh slackware"...Many people say Slackware is hard to learn, that you need to be an experienced linux user etc.

Well, I think reading Slackbook and trying Slackware you're going to learn really very much, because Slack's not so complicated as some people say.

I guess if you want to learn linux, you'll like Slackware, like me

---Edit---
Sorry, maybe I've posted too late :$

Your choice of CentOS is fine for studying to get Red Hat Enterprise Linux certification. As was already mentioned, it is just Red Hat Enterprise Linux with the trademarked items removed. There is a great deal of support for this distribution, either through CentOS forums or from the documentation for Red Hat Enterprise Linux. Certification with this distribution (RHEL) should prepare you for maintaining a server, I would think (I am neither certified nor a server administrator). All of the normal desktop application sofware is available for CentOS/RHEL, and some people use it as an end-user desktop distribution.

As far as availability of software, the .rpm format is very popular. Red Hat is a profitable company, I believe, so it should be around for quite some time.

As long as you don't get frustrated, you will find that the distributions are much more similar than different, and as an end user, someone who has used linux for a little while will normally not have difficulty being productive with several different distributions, because modern distributions all have package managers that handle dependencies (such as libraries) for you, and the typical software applications you will use are available for all reasonably popular distributions.

Do NOT start with slackware, as you will be more likely to get frustrated and stop trying to learn about linux.

what i know that Redhat5.3 is release and Centos doesn't release Centos 5.3 yet
i had found a torrent for RHEL 5.3 and it has the key too
is that sufficient to have the key or there is something i missed??

I don't know if that is sufficient. I do know that Red Hat Enterprise Linux is based on a paid subscription model, whereas CentOS is free in both senses of the word (gratis and libre). Even if you did have a "key", wouldn't that key eventually expire?

Why don't you just go with CentOS 5.2 and upgrade as newer versions come out? It is just a point revision, not a big deal, especially for use with servers.

Speak for yourself. It depends on the individual. Too many people are frightened off trying Slackware by statements like that. All you need are the abilities to read, follow instructions, and think. Average abilities.

I'll say it again. Do NOT start with slackware. Anyone who tells you to start with slackware, gentoo, netbsd, or linux from scratch is not your friend. They're like the SOB of an uncle who teaches his nephew to swim by throwing him into deep water, yelling at him to flail himself to the the ladder. LOL