Active more than 3.25G ram on vista and windows 7

1.Click Start.
2.Type CMD in the Search Bar.
3.Press Ctrl + Shift + Enter to run cmd in administrative mode.
4.Type BCDEdit /set PAE forceenable
5.If this does not work try other 2 times at least. As a matter of fact Vista does not take this command right away in some cases. Make also sure to type the command in the same way it is written on point 4.
6.If Vista got this command successfully you should see the following message: the operation completed successfully.
7.To undo it, type: BCDEdit /deletevalue PAE