A D H D More Condition_symptoms I Want To Install A Higher Volume H D D In My Laptop But I Want To Keep My Win XP OS. How To Do Please?

I want to install a higher volume H D D in my laptop but I want to keep my Win XP OS. How to do please? - a d h d more condition_symptoms

My current hard drive only 10 GB and I want to install a (used) 40 GB or more. Is it possible - and legal - to transfer my operating system Win XP on the new hard drive, and if so, can you please tell me how?
Thank you very much.