Kevin, and what is Vista Performance Score now after that upgrade? I know that´s going to be 1 but the memory score how compares with the old one?

crystalmark is just calculating how fast your memory read and write and it gives a cache score which as you can see is not the biggest number.

I would expect to see a big jump in performance between 512 and 1 Gb but the difference between 1 GB and 2 Gb wont be that big as the difference between 512 to 1Gb.

To find differences in performance because of a memory upgrade you need a more strong tool. I would advice something like this

http://www.vanshardware.com/news/2004/04/040422_OSMark/040422.htm