Are you wanting to boot back into Windows?
If so, boot the computer off of your Windows installation disk and when it comes to the screen asking if you want to install or repair, push R to enter the recovery console.
Type the number of your Windows installation and hit enter.
Now type in:
Answer yes to the question.
Followed by:
Answer yes to the question and reboot the computer.
Whatever you canceled during the installation, must have messed up the Ubuntu install, but installed the Grub boot loader. What you do with the Windows CD and the recovery console is restoring the Windows boot loader so that it can boot back into Windows.