[CentOS] Kickstart with all the latest updates?

Currently, I kickstart my machines over http to install CentOS 4.4 and then in a script called from %post do a "yum -y update" to install all the latest updates. Is there a way to set up the kickstart server so that I can do this all in one step? In other words, is there a "supported" way to roll in all the updates into the kickstart server? In case it matters, I set up the kickstart server by copying the contents of all CentOS 4.4 CDs (well, from the ISO images actually) into one directory, and then configuring the kickstart file to point to that URL (via http).

Thanks, Alfred