pxelinux.0 - Bootloader
pxelinux.cfg/default - Bootloader menu config, same syntax as isolinux.cfg
http://www.kernel.org/pub/linux/utils/boot/syslinux/syslinux-2.06.tar.bz2

vmlinuz - Kernel image, from distribution to be installed
initrd.img - Inital ramdisk image, from distribution to be installed
http://www.kernel.org/pub/linux/utils/boot/syslinux/syslinux-2.06.tar.bz2

pxeboot.msg - Text file displayed on pxe boot menu
README.txt - This file you are reading

# yum install tftp tftp-server
$ wget kernel.org*syslinux*
$ tar -zxcvf syslinux-*
# mkdir /tftpboot/
# chown -R someuser:someuser /tftpboot/
$ cp syslinux-*/pxelinux.0 /tftpboot/
$ cd /ftptpboot/
$ wget ftp://ftp.funet.fi/pub/linux/mirrors/redhat/fedora/linux/core/1/i386/os/images/pxeboot/initrd.img
$ wget ftp://ftp.funet.fi/pub/linux/mirrors/redhat/fedora/linux/core/1/i386/os/images/pxeboot/vmlinuz
$ mkdir -p /tftpboot/syslinux.cfg/
$ nano /tftpboot/pxelinux.cfg/default 
  # Perform a local boot by default
  default install
  # Always prompt
  prompt 1
  display pxeboot.msg
  # Boot automatically after 30 seconds in tenths of a second
  timeout 300
  label local
         localboot 0
  label install
         kernel vmlinuz
         append initrd=initrd.img

see also 
http://iki.fi/karvinen/pxe/
http://syslinux.zytor.com/pxe.php
http://cfm.gs.washington.edu/~adioso/HOWTO/RedHat/RHCustomCD.xml
