Just used unetbootin made a flash pendrive knoppix7.20 image to boot,
once booting with pendrive, evrything's fine.
there're bugs for samsung syncmaster 920nw lcd displaying resolution:
Knoppix7.20 can't distinguish samsung syncmaster 920nw lcd well,which should be working at 1440x900@60-75hz resolution in standard...runing Knoppix 7.20 with samsung syncmaster series Lcd, syncmaster 920nw or other model can't be able to work at standard 1440x900 resolution,under Knoppix 7.20 only 640x480, 80x600,1024x768 available....

which s old bugs for xorg, addressed many times since 2010 but still didn't put fix in xorg.conf yet...
mandriva does have good support to samsung syncmaster lcd.

hopeKnoppix would offer fix for samsung syncmaster 920nw LCD soon!