make apt-get skip some packages in upgrade

When doing an apt-get upgrade on my Debian (Lenny) box yesterday I received this message

Since release 150, udev requires that support for the CONFIG_SYSFS_DEPRECATED feature is disabled in the running kernel. Please upgrade your kernel before or while upgrading udev.

This was holding back the upgrade of all the packages. Looked around a bit and it seems that the solution for this problem is to let apt know that we do not want to upgrade the udev package. The way to do this is echo "udev hold"|dpkg --set-selections and then run apt-get upgrade