Log into ubuntu and open a terminal window. Type the following:

sudo gedit /boot/grub/menu.lst

After you enter root password you should see a text editor open. Good idea to save a copy before you edit just in case. Look at the end of the file for:

# This is a divider, added to separate the menu items below from the Debian
# ones.
title        Other operating systems:
root

# This entry automatically added by the Debian installer for a non-linux OS
# on /dev/sda1
title        Microsoft Windows XP Professional
root        (hd0,0)
savedefault
makeactive
chainloader    +1

cut this text and paste before

title        Ubuntu 8.04, kernel 2.6.24-16-generic
root        (hd0,1)
kernel        /vmlinuz-2.6.24-16-generic root=UUID=f17d8985-ddde-4679-bbdf-8c3e423b0084 ro quiet splash
initrd        /initrd.img-2.6.24-16-generic
quiet

I added a # in front of the title ‘Other operating systems:’. If you don’t, this will be the first option selected and therefore the automatic boot option is essentially disabled. If you don’t want the first option on the list automatically selected, then don’t add a # in front.

save and restart. Win Xp should now be the first on the list

I am sure there are other ways of doing this, but this works.