where does it says you have 2048, is it from the OS or is it from the BIOS settings?
if its the OS, I thinks its a glitch and I have found in the Linux forum someone with this issue I think..
Is it a glitch, or is the OS including the swap space in the total amount of available RAM? A 512Mb version, with an extra 1Gb + 512Mb of swap space would indeed come to 2Gb.