Even though Microsoft has ended support for Windows XP, there are still reasons people like yourself and myself need to use it. Upon finishing the installation you will have to activate it, which is cumbersome but very easy.
On the activation page where you will either have a 6 or 7 digit number sequences you need to give to a "rep", you will have an option to call. Select the toll free US number if you are from the US. When going through all of the prompts DO NOT select the option where they send you a link! The link gives out errors and will ask if you want a rep to call you and that rep will send you to these forums, which is hardly useful.
Instead stay on the line and then you will begin the slow process of telling the "rep" your activation codes. Once they are confirmed you will be given your access codes, I would select the option where they text them to you. Keep them on the phone while you input your access codes. Once that is completed you are on your merry way!