Here is a simple way to make your own Grub Splashimage:
Create your own Graphic image.png
convert -resize 640×480 -colors 14 image.png image.xpm && gzip image.xpm
copy image.xpm to /boot/grub/
vim /boot/grub.menu.lst
Add the following line
splashimage (hd0,1)/boot/grub/image.xpm
Note: Assuming your Linux partition as /dev/hda2