PC not booting from Windows XP CD

The Windows XP boot CD has this strange behavior where it won't boot if there is a certain level of corruption in the Master Boot Record (MBR) of your hard drive. Ideally it should ignore the hard drive when booting from CD, but it doesn't do that.

I had a similar problem -- I had a hard drive that was wiped with random data, and wanted to install Windows on it, but the Windows CD would hang when booting even though various Linux CDs would boot fine. Ultimately I had to use Gparted on a Linux CD to create a partition on the hard drive, then the Windows CD booted and let me install Windows.

You might get Windows to boot via GRUB. Install Ubuntu to a non-Windows partition, and have it put GRUB in the MBR. Then boot Windows from the hard drive by choosing it from the Ubuntu GRUB menu.