[PlanetCCRMA] About upgrades, distros and the rt-kernel

[ailo]

I've installed fc10 on three machines, all of them old.
Just migrated from Ubuntu, so I am not used to Yum.
I followed the instructions at:

http://ccrma.stanford.edu/planetccrma/software/installplanetnine.html

I updated the system. Then Installed some apps + planetccrma-core, with
the rt-kernel. Boot went fine, however logging in caused Xorg to crash.

Then, after doing some research, I decided to reinstall, and NOT to
upgrade my system before installing the planetccrma-apps and -core.
This worked a lot better, however I still had to keep the fedora-updates
checked in 'Software Sources' in order to be able to install the
planetccrma packages. This must have meant that I still needed to
upgrade a few packages from Fedoras repo in order to be able to install
some of the planetccrma packages.

I know this is not a Planetccrma issue, however, I feel a bit lost in
this update-jungle.

Keep in mind, that the 'normal' kernel worked just fine at all times, so
this must be a problem connected to the rt-kernel.

I read somewhere that the rt-kernel is always behind the 'normal' one. 
Is there a way to synchronize yum with the kernel-version you want to
use? Would it help stability?