up to date fedora core distribution

[multiscan]

Hi all,
	even a quite fresh fedora distribution ends up having a lot of updates.
I wander if it is possible to replace the original rpms in the
distribution media (on an nfs server) with their updated versions. When
I've tried it did not work. Probably due to problems with the repodata
or similar.
At present, in order to avoid installing a lot of packages that are
going to be replaced imediatelly after, I just install the basics within
kickstart %packages section, and then install everything else with yum.
It would be nicer to be able to do everthing at the same time. 
What are the exact steps needed in order to keep my version of the core
distro up-to-date ?
Thank you very much in advance for any suggestion.

giovanni


p.s.
I've been browsing the mailing list archives looking for a similar
question but I could not find one. It would also be very nice if there
were a sort of search engine for the archives.