My notebook has a stick of Samsung (M470T6554CZ3) PC2-5300 DDR2 512MBytes memory. I want to add a stick of 1Gbytes PC2-5300 Trascend or PC2-5400 PQI or OCZ Value into the notebook. Do you think there is going to be a problem with a non symmetric upgrade (one side has 512 Mbytes and another side has 1Gbytes)? Which of the three brands do you recommend?