Windows xp in a linux OS

Hello,
I just bought a netbook, which it hasn't a cd drive right... and I want to install windows xp in it when booting the netbook since it keeps asking me for a password at the login and I don't have one. I bought the computer used and the guy that I bought it from told me he'll do it for me if I pay him 50 dollars; I think he did all this on pourpose to charge me. So, please somebody help fix his without having to go thru that guy.