I used to use my i-Trigue 3400 2.1 speakers on my desktop pc. Now i sold the pc and kept the speakers. Today i plugged the green 3,5mm jack into my new MBP 2,8ghz 15" but it's not working/recognized. Is it compatible with MBP at all?

I thought the same, the speakers are speakers. But i can't get them to work! These are screenshots of my sound preferences (tho they are italian, i put a translation in there)
ok, i presume i have to try other speakers to be sure that i can be a broken audio port. how could the drivers be corrupted if i have this mac since 2 days only. Fresh install. I feel unlucky..
Ok, now i'm feelin kinda stupid, but what port do i have to plug my speakers in: the earphone hole or the other one?
I just plugged them into the earphones and they work, but they are recognized as earphones in the sound preferences. Is that right? If yes, what is the other hole for?