if you have 32 bit version than that is right! if you are using 64 bit then follow these steps.
1.click on start button and select run
2.type "msconfig" press enter a windows will appear look at the top BOOT.ini option and select it.
3.now after that click on "advanced option"
4.now tick the first box and increase the memory of it's maximum level then click on OK and reboot your system.
thanks!