Windows XP is the latest offering from Microsoft. There have been a number of Operating System's released since Windows 98 Second Edition and I think you would benefit from staying with Windows XP, the latest applications are made to take advantage of XP technology and may not run on a 98 machine. HP build their machines to intwine closely with XP, you should check to make sure all the required drivers are available before installing 98 (I couldn't get a 98 driver recently for a TFT screen for instance). You can make XP more "classic" if thats what you would prefer and can download themes to take this even further.