well yor sys config shows u have a total of 6gb but your using 4gb i dont know for what so thats why it says 2gb avaliable,if what nickoff said wont work reinstall windows
Addressable memory (memory utlisation) and triple-channel configuration is two independent things and not related.
i.e. you can have 6GB, but not necessary triple-channel.
Reinstalling same version of Windows will not help with addressable memory.
The question at hand has been answered and is simply a matter of incorrect reporting by 'System Information' which does not affect actual operation.