64 bit - Tell the version of Windows XP (64-bits or 32-bits)

My laptop's CPU is the Intel P8600 (x86-64 architecture), and Dell pre-installed Windows XP SP3 on it.

However I am not sure if the version of Windows XP is the 64-bit version or the 32-bit version; can someone tell me how to find out the answer?

I am asking this because I want to install a proper JRE with good performance on my system.