There are almost as may techniques for doing this as there are reasons for not doing it. The article linked to is ecxellent. Others have different methods. Many say that you should always do a fresh install. I tend to agree with the fresh install but have linked to that article myself for others that didn't want to go through the hassle. Bottom line to me is this: if you MUST try to do an upgrade without reinstalling XP then you should study that article and any additional info you might get, then give it a try. If all works well, congrats; but still plan on doing a reinstall sometime in the near future. You don't necessarily have to, it's just a good idea. There are other benefits that can be had from a fresh install. First and foremost is that your system will be much "snappier" and perform better for you. Windows, no matter what version, tends to bog itself down over time. Yeah, it's not as bad with XP but it is still there.