Zalman,
MS Project is an application - in particular a planning and scheduling
application. There are amny versions of Project, the latest being
Project 2003. On the other hand, XP is an operating system.
You can buy the most current version (there are server and professional
variants) of Project from most any software supplier. If they don't have
it directly, they can order it for you. Most earlier versions of Project
are also available. A software supplier may have one or more versions
left over or more likely, earlier versions can be found on internet
auction sites such as eBay.
I must admit, reading your post makes me wonder why you are interested
in Project.
John
