How do I re-install windows xp from an extern

Hello,

Last year the matherboard of my computer got spoilt so i had the hard drive extracted and made into an exteranal one by putting it into a hd casing.
and it works fine
but now i have another computer which got corrupted and cant restore it i want to re install the windows xp operating system to this computer but i want to use the one on the extal hard drive
is it posible and how do i do it please help