If this is a windows 7 32bit the 2GB of RAM should be ok but Norton maybe dragging it a bit. But I think it is most likely the "Virtual Memory" the alert is concerning, here is a quick an simple fix.

On the start menu right click "Computer and the left click "Properties then select "Advanced" and under "Performance click on "settings". Again select the "Advanced" tab then near the bottom you'll find "virtual memory" and click on the "change" button and increase the setting or select "system managed size" and then click "Apply". The system will need to restart then.