You have the 32 bit edition of XP. There's a version of XP that's 64 bit,
but it only runs on the Intel Itanium processor (think Pentium on steroids,
and growth hormone). This configuration would be found in extremely high-end
workstations - machines used for mechanical engineering, 3D animation, video
editing, etc. You would know if you had such a machine - being that they
START around $3,000 (the HP's, for instance).
Patrick Pitre