Could anyone suggest me what repository has most updated packages for CensOS? and a briefly instruction how to install that, please. I use RPMforge for now, not sure if it's good enough though. Thanks!
I'd have to say RPMforge. The guys over at CentOS even tell you to refrain from installing certain packages from RPMforge, as they may be newer than the official CentOS versions!
See Installing RPMforge for further information.