This may be a stupid question, but if I don't ask, I won't learn. I have an IBM Think Pad that had 256mb of RAM (two chips of 128 each). I removed one of the chips and installed one with 512 mb of Ram. When I right click my computer on the desk top it shows "646,512kb Ram." I was expecting it to show something just shy of 740mb (512 plus 128). How many mb of Ram do I now have? Do I divide 646,512 to arrive at 646.5mb? If so, where is the rest of my RAM?