Not sure if your installed version of Windows is 32-bit or 64-bit? One quick way to tell is by looking at information about your operating system installation in Control Panel.

XP 64-Bit Edition Version 2003. Windows XP 64-Bit Edition Version 2003 is optimized to enable customers to take advantage of the performance enhancements in the Intel Itanium 2 processor. Windows XP ...

If you're updating a 64-bit machine (substantially less likely, coming from Windows XP), grab the 64-bit tool. I just let these tools download to my Downloads folder and then executed them.

My question is what are the drawbacks of running the 32-bit version of Windows XP on dual quad-core Xeon processors? Will the OS be able to utilize the 4-cores in both processor?