Repositories don't always work together, so you shouldn't indiscriminately add repos. Repositories that never conflict with each other are the Fedora default repos(including Extras) and Livna. You could also use FedoraFAQ's repo configuration (http://www.fedorafaq.org/#installsoftware) if you want.

I've also used atrpms, dags and dries repos for certain applications.

Follow this guide: Stanton Finley Fedora Core 4 Installation Notes (http://fedoranews.org/mediawiki/index.php/Fedora_Core_4_Linux_Installation_Notes)

thanks everyone, that helps.