1) That's not enough memory, 512 should be considered the minimum
2) Can you please post whatever you are doing prior to the error and what messages if gives you. Is that upon initial boot of the DVD, the HDD, or is during the install process... I need a lot more information
3) Doing a quick google brought this as the first result... http://ubuntuforums.org/showthread.php?t=292533
... A little research on your part would be nice...