also if you want to burn (i mean erase) absolutely everything on the hard drive you can do "sudo dd bs=1M if=/dev/zero of=/dev/sda" or hda or whichever way the hard disk is detected with your boot disc/usb. there is no progress meter, but dont worry it'll probably finish in like an hour or two depending on things. bodhi linux and xubuntu are two lighter weight alternatives to ubuntu based on ubuntu.