XP was made for much weaker machines, older hardware. When you earn 100 USD per week you don't upgrade hardware as long as you can. Just as an example from another part of the world, I live in Europe and I've used a Sony notebook from 2002 until the last year, when the hardware started to fail. I guarantee you that Windows 7 can't be installed on it. Even the newer Ubuntu versions weren't installable from one point on.