[quote author=“writetovarun”]Its a 64 bit windows version designed for use with 64 bit processors.
To go a little further… it supports the 64-bit processors’ “enhanced” CPU cycles which will let the O/S send commands to the CPU while better using its cycles to their optimal limit…
These are the “Top 5 Reasons for Switching”... but they arent exactly true in all respects:
[quote author=“Microsoft.com”]High Performance Platform for the Next Generation of Applications
Windows XP 64-Bit Edition is a rich platform that enables the next generation of high-performance computing. 64-bit native applications can deliver more data per clock cycle, making them run faster and more efficiently.
Large Memory Support
Windows XP 64-Bit Edition will currently support up to 16 GB of RAM and 16 TB of virtual memory, enabling applications to run faster when working with large data sets. Applications can preload substantially more data into virtual memory, allowing rapid access by the 64-bit processor.
Compatibility
Windows XP 64-Bit Edition provides a rich platform to integrate 64-bit technical applications and existing 32-bit business applications using the Windows on Windows 64 (WOW64) x86 emulation layer, providing customers with the ability to move to 64-bit computing without having to sacrifice their existing investment in 32-bit software and Windows expertise.
Multiprocessing
Windows XP 64-Bit Edition is designed to support multiprocessing capabilities for maximum performance and scalability, supporting up to two symmetric 64-bit processors.
Same Programming Model
Developers with 32-bit skills will be comfortable and quickly productive in the 64-bit Windows environment, finding it virtually identical to the development environment for 32-bit Windows.
And here are some product info links:
64-bit OS Overview
64-bit OS FAQ