I haven't bought a computer from Overstock but I've bought enough other things from them to believe that you shouldn't have a problem.

Have you checked out tigerdirect.com? They have some good deals and I think they still have some XP operating system computers.

If you need any help or have any questions about computers, please feel free to ask. I've built my past two computers and most of my past jobs have included me being the tech person. :-) People at work bring their computers to me to fix 'em.