Windows XP takes portions of the operating system, applications, and data files that aren't currently needed in RAM and temporarily stores the data on the hard disk in the paging file. During a normal computing session, Windows regularly moves data back and forth from RAM and the paging file.
If you have a considerable amount of RAM in your system—512 MB or more—you can improve system performance by preventing the OS from sending user-mode and kernel-mode drivers, as well as kernel-mode system code, to the paging file.
You can do so by changing a setting in the registry. Here's how:
Session Manager\Memory Management.
You may need to restart the system or log out of Windows XP for the change to take effect.
Note: Editing the registry is risky, so be sure you have a verified backup before making any changes.