You need to do change the default= line in /etc/grub.conf.
Code:
timeout = 5
splashscreen = (hd0,1)/boot/message.col24
default = 0
title = Linux
root = (hd0,1)
kernel = /boot/vmlinuz-pc97-2.2.14-modular vga=274 noapic nosmp
#this is the XP entry
title = WindowsXP
chainloader = (hd0,0)+1
Each Title is numbered starting at zero.In this example to make XP the default you would change the Default=0 to Default =1
You must do this with a text editor as root.
HTH
lynch