Question about windows xp

I currently have winxp pro but I got it from a friend so I can't install sp2 on it. My question is can I just install the new xp over my current one or do I have to do a clean install?

 

Actually, I think that it was three questions. If you have XP Pro and it is working, then there isn't any reason that you shouldn't be able to install SP2, unless you have a pirated version and haven't installed SP1 yet. If that is the case, then you won't get any help on this site. I'm not assuming or judging, and only going by what you stated in your post. If I am wrong in this, and there is a legitimate reason that you can't install SP2, please reply, and I will give all the help that I can.