TCOS

"TCOS is a free software project, it consists in creating a micro OS (debian/ubuntu based) that when copied into /tftpboot root dir it gets served to a thin client network (pentium 350 64 Mb ram), this will boot terminals and connect by XMDCP to the server where the users can login and work. The idea is based on PXES project but TCOS uses newer kernel without patches and recognizes newest hardware."

http://soleup.eup.uva.es/mediawiki/index.php/TCOS/en

http://soleup.eup.uva.es/tcos/

http://soleup.eup.uva.es/tcos/screenshots/