Do you want to increase or decrease the Grub loader time-out during an XP-Ubuntu Os selection in a dual boot ?
The method is simple and straight forward .
Just open the Terminal / Console ( Application –> Accessories –> Terminal)
Type the following and hit <enter>
$ sudo vim /boot/grub/menu.lst
You will be prompted to enter the password . Go ahead and enter your password and hit < enter > .
What you have actually done is to open the menu.lst file as a root user ,using an editor like vim .
You can also use an editor of your choice , say kate or leafpad.
In this case you should type
$ sudo kate /boot/grub/menu.lst
or
$ sudo leafpad /boot/grub/menu.lst
In menu.lst file , search for the word “timeout” .It would be set to the default value 10 , like the following :
## timeout sec
# Set a timeout, in SEC seconds, before automatically booting the default entry
# (normally the first entry defined).
timeout 10
Now change the time-out value to 60 and thus it should look like
## timeout sec
# Set a timeout, in SEC seconds, before automatically booting the default entry
# (normally the first entry defined).
timeout 60
Thats all !
if you have used vim or vi editor for viewing the menu.lst file , then press <esc> then type :wq and then hit <enter>. Thus you have saved and quit the editor . If you use leafpad or kate , just “save” it and quit .
All done !
Reboot and feel the difference !
Happy ubuntuing 
Article updates:
You may be wondering that menu.lst is not found in karmic koala(ubuntu 9.10). Thats because Ubuntu 9.10 has moved on from Grub legacy to Grub2 (or grub-pc as the package is called). Editing menu.lst is a thing of the past. Grub2 uses grub.cfg which is automatically generated from script. DO NOT EDIT /boot/grub/grub.cfg. Instead edit the timeout or default OS to boot in /etc/default/grub. Changes made in this file will be imported into grub.cfg when “update-grub” is executed.
so in short, ubuntu 9.10 users should the following commands (in order):
$ sudo vim /etc/default/grub
make edits then run the following command
$ sudo update-grub
