rebuild everything - howto? please help me

[dima]

I come the sorry!!!!!!
Good Day! Please help me. Tell me, step by step, how to rebuild all system? (not only kernel or one package - but all) example for core cpu. In internet i find links "Howto to Rebuild RPM Packages under Red Hat Linux" http://www.willert.dk/geek/rebuild.html, but if i have 100000 packages - it's not possible rebuild this method it is a lot of packages, i think exists script or other method for this purpose
O'key, example - i have Fedora XFCE i686 disk, but i want rebuild all system for core2 (gcc 4.4 support core2 option), no visualizations or other
programs who need old i586......only Fedora XFCE i686 about 609M (not important 609M or 624M) how????? 
Thanks. Good Luck!!!