Virtual memory is, in fact, the memory space allocated on
a hard disk that is used by your operating system as a
RAM to improve the performance of your computer.
In Windows 7, you can change the size of your virtual
memory by right clicking on your Desktop and selecting
Properties. Then, click on the Advanced system settings
link in the System window.
Choose Settings under the Performance section. Select
Advanced tab and click on Change under the Virtual Memory
section. Then, uncheck Automatically Manage Paging File
Size for All Drives. You may now select your virtual
memory size. Set, exit, and restart.