Perhaps your son has damaged the WinXP installation; perhaps not. You said this:
He was in the process of installing Ubunto where it talks about disk partition when I stopped him and made him cancel out.
That's very vague. How far into partitioning did he go? Was it far enough into the installation process to write the Ubuntu bootloader to the Master Boot Record (MBR) of the hard drive? If so, you can't boot widows because it's bootloader in the MBR has been overwritten. Had the installation actually begun? Did he start installing without creating a seperate partition for Ubuntu, seperate from Windows?
Check the documentation for your PC. How do you get into the BIOS? It's probably something like 'hold down the delete key during power up when you turn on the computer'. It may be a bit more involved as to what key(s) to press during power up to get into the BIOS. Go into the various menus until you find the one in which you specify the boot order (the order the BIOS will poll various devices looking for a bootable operation system). Make sure that your CD drive is polled before the hard drive. If the cd drive is polled first, then your recovery disk should boot. You want to restore the WinXP boot loader to the MBR.
I'm not a windows user anymore (gave up the habit years ago). I beleive the command is 'fixmbr' to restore the MBR. You might want to use another computer and point the web browser at www.google.com/microsoft
and search for 'fixmbr' to see what comes up. You could also try www.google.com/linux
and search for 'fixmbr'. At any rate, once you can run fixmbr from the recovery cd, you should be able to boot windows.
For future reference, you need to resize the windows partition to create free space to install Ubuntu, or any other flavor of Linux. Then, during the installation process, select that free space as the place to install Linux. That way, windows isn't affected.