Yep -- and Apple has some new anti-piracy measures in Tiger that automatically "phone home" to Apple's layers' offices whenever it detects a system disk that shipped with a certain kind of computer being used in a different computer. It doesn't do it by network, either, so disconnecting your computer from the internet won't work. They have special homing pigeon eggs in the computer whose life energy is activated when you do this, then they grow and secretly exit the computer when you're not looking.
Then your head blows up -- I've seen it happen to this dude one time. I was all like, "No, dude, don't do that -- the license agreement says 'one installation,' not 'two installations,' dude!" And he was all like, "Dude, it's cool, man... this stuff's overpriced anyway, and I can't afford two copies. I don't understand why it's illegal anyway." and he went and did it despite my warnings.
Ruined my shirt that day -- I still can't get the stains out.
Suggestion: go purchase Tiger like you're supposed to.