Linux PPP operations come in two parts
the PPP daemon mentioned above
kernel support for PPP
Most distributions seem to provide PPP kernel support in their default installation kernels, but others do not.
If at boot your kernel reports messages like
PPP Dynamic channel allocation code copyright 1995 Caldera, Inc. PPP line discipline registered.
your kernel does have PPP support compiled in.
That said, you may want to compile your own kernel, whatever your distribution, to provide the most efficient use of system resources given your particular hardware configuration. It is worth remembering that the kernel cannot be swapped out of memory and so keeping the kernel as small as possible has advantages on a memory limited machine.
This document provides minimal kernel re-compilation instructions at section Chapter 10.
For greater detail, see the Kernel-HOWTO at The Linux Kernel HOWTO