grub2 - How to boot Windows XP (no GRUB menu is shown)?

I installed ubuntu 12.04 alongwith with Windows XP. But the system directly boots Ubuntu without giving grub selection menu. I opened a terminal up (ctrl-alt-t) and typed in the following:

sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update

Then my password and followed by:

sudo apt-get install -y boot-repair && boot-repair

But i got the message as follows:

BuildiReading package lists... Doneng dependency tree       
Reading state information... Done
E: Unable to locate package boot
E: Unable to locate package repair

So now what should I do? Please help as I cannot access Windows XP...