Thank you for the answer MrNovi.
Yes, I know what you say, but my question was about "accepting code" from internet when browsing or ports opened to be exploited. If I donīt accept scripts from internet and my ports are all closed or filtered, well... as you say I imagine there are many other forms to hack the computer, but I am with you in these words: not a extended period of time. Thatīs what zeusgard in fact does: 30 minutes maximum and shutdown.
So, if for example I only want to check my bank account or to change my passwords, etc... and I "suppose" my knoppix is malware free (who knows...) I think itīs a good way to be secure. And I donīt need to pay zeusgard to be more secure, knoppix is enough and itīs free.
Normally I use knoppix in my pendrive with persistence, avoiding scripts everytime I can and thinking to get a pendrive with read-only switch.