其实修改Ubuntu安装后的双系统启动顺序很简单，修改 /boot/grub/menu.lst 文件，使其中default值变动一下即可。
过程如下：
1、打开命令行终端；
2、输入：
sudo cp /boot/grub/menu.lst /boot/grub/menu.lst.bak
sudo gedit /boot/grub/menu.lst
注： 第一句做备份用。
3、假设文件内容如下：
# menu.lst - See: grub(8), info grub, update-grub(8)
# grub-install(8), grub-floppy(8),
# grub-md5-crypt, /usr/share/doc/grub
# and /usr/share/doc/grub-doc/.
## default num
# Set the default entry to the entry number NUM. Numbering starts from 0, and
# the entry number 0 is the default if the command is not used.
#
# You can specify 'saved' instead of a number. In this case, the default entry
# is the entry saved with the command 'savedefault'.
# WARNING: If you are using dmraid do not change this entry to 'saved' or your
# array will desync and will not let you boot your system.
default 0
## timeout sec
# Set a timeout, in SEC seconds, before automatically booting the default entry
# (normally the first entry defined).
timeout 10
## hiddenmenu
# Hides the menu by default (press ESC to see the menu)
#hiddenmenu
## ## End Default Options ##
title Ubuntu, kernel 2.6.15-23-386
root (hd0,2)
kernel /boot/vmlinuz-2.6.15-23-386 root=/dev/hda3 ro quiet splash
initrd /boot/initrd.img-2.6.15-23-386
savedefault
boot
title Ubuntu, kernel 2.6.15-23-386 (recovery mode)
root (hd0,2)
kernel /boot/vmlinuz-2.6.15-23-386 root=/dev/hda3 ro single
initrd /boot/initrd.img-2.6.15-23-386
boot
title Ubuntu, memtest86+
root (hd0,2)
kernel /boot/memtest86+.bin
boot
### END DEBIAN AUTOMAGIC KERNELS LIST
# 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/hda1
title Microsoft Windows XP Professional
root (hd0,0)
savedefault
makeactive
chainloader +1