I understand that this issue was raised many times now. After searching google in Polish, italian, English, Russian, Turkish, Ukranian, and Dutch (German), I have found that only one guy succeeded in installing 3 GB (1+1GB and 1+2GB) RAM on his Amilo Pro V3515.
When I email Fujitsu Support service, they give their usual: "it will support 2 GB max" thing.
What to do? Anyone had experience with this?