[Barkotron]

Note that you may also need to fiddle about with your BIOS settings to get the memory mapping to work correctly. Even with Vista x64, my machine showed just under 3GB RAM available with 4GB installed until I changed a setting in the BIOS.

I think my board called it "enable memory hole", but I've heard it called "memory remapping" as well. If you install 4GB and don't see the full amount in your x64 operating system, have a look in the BIOS for a setting along those lines, and enable it.

EDIT: blimey, blast from the past. Didn't realise this was from so long ago, sorry for dragging it up again. I keep forgetting that the "related posts" thing is so wide-ranging.