you're correct,
Code:
# yum update kernel
does the trick.
It *shouldn't* break anything, however, some of the packages you've installed may be kernel-specific (ndiswrapper, for example), so it may be wise to update all your packages, either whilst updating the kernel, or shortly thereafter (especially if some packages don't work...)
Of course, you can pick and choose what packages you wish to update, as a full update could take hours.
Also, if updating just the kernel 'breaks' your system, GRUB will allow you to boot into the previous kernel.
cheers,