excerpt from CHANGES_AND_HINTS.TXT

It is recommended that you use one of the generic kernels either
the plain kernel-generic or kernel-generic-smp) for daily use.
For most systems, you should use the generic SMP kernel if it
will run, even if your system is not SMP-capable.  Some newer
hardware needs the local APIC enabled in the SMP kernel, and
theoretically there should not be a performance penalty with
using the SMP-capable kernel on a uniprocessor machine, as the
SMP kernel tests for this and makes necessary adjustments.
Furthermore, the kernel sources shipped with Slackware 12.0 are
configured for SMP usage, so you won't have to modify those to
build external out-of-tree modules (such as NVidia or ATI
proprietary drivers) if you use the SMP kernel.

If you are using one of the non-SMP kernels (huge.s or
generic.s) and need to compile third-party modules (such as the
proprietary NVidia driver), have a look in
/extra/linux-2.6.21.5-nosmp-sdk/ for information on what is
needed to build them.

As stated earlier, it is recommended that you use one of the
generic kernels rather than the huge kernels; the huge kernel is
primarily intended as an "installer" and "emergency" kernel in
case you forget to make an initrd.

However, if you do use one of the huge kernels, you will likely
encounter errors like this:
    kobject_add failed for uhci_hcd with -EEXIST, don't try to
register   These occur because the respective drivers are
compiled statically into the huge kernels but udev tries to load
them anyway.  These errors should be safe to ignore, but if you
really don't want them to appear, you can blacklist the modules
that try to load in /etc/modprobe.d/blacklist.  However, make
sure you remove them from the blacklist if you ever decide to
use the (recommended) generic kernels.