I am a happy user of the xo (usually running ubuntu, see
http://www.olpcnews.com/forum/index.php?topic=4053 ), however 256MiB of ram isn't too much... I found these instructions
how to add a second ram module. I am pretty confident to do the soldering, however I am not sure if it will work with openfirmware (the instructions mention how to enable the extra ram in the Insyde Embedded Bios).
Do I need to change some openfirmware settings to see the extra ram? Can someone provide more information / instructions?