this is a pretty neat thing a classmate of mine showed me. linux means you can customize every part, right from the background desktop color to the kernel. i'll show you how change the boot screen background image. i am assuming you are using grub as you boot loader and not lilo. you'll have to login as root to perform these changes.
step 1. making an image file
open any image editor; i used gimp. and make the image file you would like to show on boot. remember not to make a "heavy" image as during boot time the graphics drivers are not loaded and you might just get a dark screen. save the image file as *.xpm.
step 2. gzipping it
$ gzip -v *.xpm
this command will create a *.xpm.gz file. move this file to the /boot/grub/ directory. you will find a splash.xpm.gz file here. this is the current splah screen and we are going to replace it.
step 3. changing conf files.
in /boot/grub open the grub.conf file. this the the grub configuration file. i suggest creating a backup file just in case. the options are
default=1 or 0 - this is used to select which os gets default boot priority. time to chane to linux. the order is based on order of title definitions below,
timeout=10 this is the time after which the default os boots. change to a small time if you are hardly using the other os .. read windows.
this is the line we are actually interested. comment the old line be preceeding it with a hash #. and add your *.xpm.gz path here.
title can be changed to suit your mood. but i have no idea of the other lines. those are grub commands.