Also referred to as a paging file or swap file, virtual memory is space on your hard drive allocated for use as memory for the running of applications. While it's not nearly as fast as physical RAM, it acts as a supplement for tasks that don't need as high of a transfer rate or are performed less frequently.
To adjust the settings for your paging file, right-click My Computer, select Properties, select the Advanced tab, click Settings under Performance, select the Advanced tab, and click Change. It's usually best to let Windows handle it by setting it to System Manages Size, but you can set a custom value if you like. An old rule of thumb was 4 times the amount of physical RAM, which would work in this case, provided you have the hard drive space to spare. Thus, you'd want to set the min and max values to 1000, click Set, then OK your way out. Restart your computer and try again.
Hope this helps,
i have been having a problem lately while playing games such as nfs most wanted.while playing , the game suddenly crashes and i come back to the desktop.a message "windows virtual memory minimum too low" appears.i have windows xp with sp2,256 mb ram,geforce 6200 with 512 mb.what is windows virtual memory? how can i rectify this problem?