Aspire 5612z memory upgrade problems resolved?

After advice from Acer and Crucial decided to upgrade from 1Gb to 2.5Gb.
2 x 512Mb to 2Gb + 512Mb (both DDR2 PC5300 667 Non ECC CL=5, 5-5-5-12).

The reasons for choice being numerous but influenced by fact Vista 32bit can't use much more than 3Gb and not loosing much for not using matched pairs apart from the extra ram itself.

Acer MISINFORMED me that 2nd memory slot was under the motherboard which I later found out to my annoyance wasn't true...its double stacked (one on top of other but slightly staggered under the notebook memory cover and EASILY accessible!!!).

Crucial told me the master socket must be used first for any single module
upgrade which I found to be true. If you swap the 'top' slot the notebook won't boot. Swapping the one underneath worked ok.

Checked Vista performance index after upgrade and surprised to note graphics index (the lowest of the measured parameters) reduced from 3.0 to 2.2...(Aero graphics 2.2, gaming graphics index no change at 3.0) Was 3.1 Aero, 3.0 gaming graphics prior to upgrade.

Changed graphics available memory in Bios (3.33) from 64 to 128 (without knowledge of if it would work and Aero index went to 2.4 with no problems..there was another option DVMT but index didn't increase again so reverted to 128Mb to be safe (I hope).

Can't understand why adding memory should be lower the Vista performance index. Must say notebook feels more responsive but not dramatically so.

Not sure whether to go the extra mile and get another 2Gb as not sure any
benefit apart from maybe the benefit from matched pairs. Although as I bought a single unit they would be identical specification modules rather than a matched pair. Would that give a problem/not work ?? Inclined to stay as is for now as getting reliable info on what will work not a simple exercise.

By the way removing cover was fairly easy if you go steady with the tabs on the cover edges(they are about 1mm projections some with a small 'L' hook shape to them, on 3 sides of the cover ..I used a blunt nosed knife marginally inserted just under the cover and with gentle pressure the cover springs clear. You can feel them if you gently run knife/object along join...I cant guarantee this method will work for you so do it at your own risk!!!

Found it slightly harder to get cover back on with tabs fully engaged...again gently does it after various combinations of which tabs to engage in what order....the last one being the hardest.
Be careful and put laptop on something very soft as I scratched the top lid when laying it upside down inspite of laying it on a plastic mat...very easily done!!


Any comments based on your experiences appreciated.