Thank you all. So now I have to buy a lan card for the first PC (because in the schematic I made, the PC with internet has 2 Lan cables connected but only one LAn port). I found a cheap Lan card with only 5 Euro plus some for shipping. And the card I will buy has only 100 speed, enough I think for the internet. And I will use the integrated Lan port with the 1000 speed in order to have a 1000 speed connection with all other PC's. - No problem using a 100 card in a pc ? No conflicting with the integrated 1000 Lan ?