Last Kernel update left me without initramfs

Hi all, with Fedora 13, the last kernel update left me without the file intirmafs in the /boot partition. All the rest is there, and I was wondering if there is an easy way to build this file myself... Any tutorial available for fedora? I tried to use the previous kernel file just by renaming it but it won't work. I get an error from iptables (can't have the slightest idea why) and from the nvidia drivers (this I guess since I installed the new ones together with the last kernel, so the old intiramfs has some reference to the old nvidia drivers module??) Any hint appreciated. Otherwise, I would just wait a couple of days and installa Fedora 14... although this seems to me a very windows-approach style :) BTW, can someone explain to me what checks are being made by yum to ensure that this doesn't happen? Thanks in advance, Fede