I don´t use any kind of firewall and i really don´t care.

sigh..you should...because one of these days men with black suits might be banging on your door because your box has been compromised and is running zombie attacks on government or commerical sites...

some isps are starting to boot customers who are recklessly disregarding computer safety...and i think you'll see a lot more of this...

i can even foresee a day..where you may be legally liable for attacks from your computer...whether you knew about them or not...your failure to "take precautions" could be seen a negligence...