Some help on half life 2 please?

Hi,

i just bought hl2 and i tried it on one of my computers and everything is fine. Now the problem is how do i install on the other computer just to play offline. I know that u can only register that cd key only once but is there a way so that i can play half life 2 in offline mode? Im not talking about the first computer, that one is fine.

please help me on this one, my hands are tied.

u just install onto ur other computer, login using ur steam account, and it should already be validated and that, and then when u try and use it offline it should work