I had a PC with Ubuntu and Windows 7 installed and I wanted to Install Windows XP on it. I installed it and then used boot-repair to repair the bootloader; I thought that I would get a screen asking whether I wanted to load Windows 7 , Windows XP or Ubuntu, but it only gives me options for Windows 7 and Ubuntu, while XP has disappeared. Any idea?
If there is no need for a native installation oft Windows XP I'd advice you to use kvm-qemu or hyper-v running XP as a guest OS instead oft wasting a partition for XP. The benefit oft this approach is the that you can keep you XP as as large as really needed and you need not to struggle with bootloaders etc.
Please note that hyper-v must be downloaded from MS and Windows 7 isn't supporting all its features thus it was introduced with windows 8.