Did somebody can give me some
advises on hardware for building a Centos linux server?
Depends on what you intend to to with it.
If you are going to just run a firewall - the cheapest, slowest,
smallest server you can buy will do fine. If you are going to
support the newest 'Hot Thing(tm)' on the net and handle 500,000,000
web page views a day you are going to need heftier hardware.
You did the equivalent of asking 'can someone give me some advice on
buying a truck?'
Before any possible answer can be given, the first question must be:
What do you plan to do with it?