Why lose 2 sticks so he is only running on 2GB? I was running on 2GB for while and i notice a considerable difference between 2GB and 4GB especially if your on Vista.
Bump up multiplyer and also maybe give the NB a few more V.
I am running 4x1GB and so far Overclcoked my E7400 to 3.8Ghz @1.31V will go for 4GHz soon.