I am working with RedHat 9 and have found that at some point in the past, after using "up2date", when I rebooted I was presented with a menu offering me a choice of kernels. Two items appeared in the list: kernel-2.4.20-8 and kernel-2.4.20-28-9. The default selection is kernel-2.4.20-8 and that is what the system has been booting under to date.

I have recently install a number of applications including MySQL and am wondering if there will be any problems with the way MySQL and other applications run if I select the other entry in the list (the next time I reboot), which I assume is the newer kernel?

Does selecting it simply ensure that my system has all the benefits of the latest kernel? Will my applications (installed from tarball) still function properly?

Thanks for your time!
Derek

There's no problems... Your applications will still work properly. Nevertheless, they may not use new functionalities of your new kernel as they are compiled with new kernel headers.
The problems you may have are about drivers... if you insert drivers after booting, you may have error messages that say your drivers are not compiled for the right kernel... but you can always ignore these messages with -f option of insmod if you you don't want to (or cannot) recompile them.