XP doesn't have MTP drivers. Windows didn't have official support without installing WMP 10/11 until the end of Windows Vista/beginning of 7.
I would try another USB port. The ones on the back of a machine have more power than the ones in the front. Some people say to use a powered hub, but the server option would be cheaper/easier.
http://manual.calibre-ebook.com/faq....kindle-fire-hd
Windows 8 would work, but I honestly would not recommend upgrading. It's just the most awful Windows version ever, and I've used them all. Like seriously, it's great for someone who has never touched a computer in their life, but not for someone who has been using Windows for the last five years or more. It's a huge learning curve.