Virtual memory is an extension of your computer's physical memory (memory chips or RAMs). In order to be able to run multiple programs at once, the computer looks for areas of RAM that have not been used recently and copy them onto the hard disk into so called page files. This frees up space in the RAM to load the new application.

 

Give a right click on Computer, then go to properties, on the Advanced TAB click on the Settings under Performance. On the new window, go to Advanced TAB, click on Change under Virtual Memory and change the values for the virtual memory there...