Before attempting to increase the amount of virtual memory in your computer system it is important to have an understanding of its purpose and usage. In the Microsoft Windows operating system virtual memory serves as the reserve memory address that supplements the existing Random Access Memory (RAM) modules installed on your machine.

For example, if you have two gigabytes of RAM installed and it has been used up by all the actively running programs, the operating system will invoke the virtual memory. This results in the continuous usage of high performing tasks as well as maintaining multitasking capability. When virtual memory is not turned on in the computer system, the machine would automatically lock up or hang once the RAM has been completely allocated.

Essentially virtual memory allows for the freeing up of memory space in the RAM by using a portion of the hard drive as a type of memory storage address. The drawback to this method is that comparatively, the hard drive accesses information slower than a RAM module. This means that there may be a slowdown in data processing once the computer system shifts to virtual memory addressing.

Taking into account how virtual memory works and its usage in a computer system, there is no ideal amount of virtual memory allocation. The amount of virtual memory to be defined for a particular computer system would be dependent on the types of applications that are launched and the amount of multitasking done. The Microsoft Windows operating system however does provide a suggested baseline memory according to the amount of RAM installed and storage space of the hard drive.

Virtual memory allocation actually refers to the increase in the size of the paging file. This file provides the computer system with the necessary instructions on how to behave once all the installed RAM has been allocated to the running programs. In both the Microsoft Windows XP (all versions) and Windows Vista environments, the way to manipulate the paging file size are essentially the same. To increase the amount of virtual memory:

1. Click on the Start menu and select the "Control Panel" option.
2. Once the Control Panel window is launched, select the "Performance and Maintenance" category.
3. Click on the "System" option to bring up the System Properties Window. (An alternative is to click on the Start menu and right click on the "My Computer" option and choose "Properties").
4. Click on the "Advanced" tab and select the "Settings" button under Performance.
5. In the Performance option window click on the "Change" button under the Virtual Memory category.
6. Select the hard drive where the Windows operating system is currently installed. This is also the same location where the paging file will be stored.
7. Check on the checkbox for the "Custom Size" to allow you to define the amount of virtual memory you want to use for your machine.
8. Click on the "OK" button thrice to close all the windows. Click on the Start menu and restart your machine to allow the increase in the amount of virtual memory to be completed.

In setting the amount of virtual memory you will need to put an initial and a maximum value. It is recommended that both values be equal in order attain the best performance for your computer system. Normally the minimal amount of virtual memory should be about twice the amount of RAM installed in the machine.