Sorry, But This Needs to Be Said
How much of a cheapskate do you have to be not to spring the extra $20 to get the product that you can legally install on up to 5 machines? We're talking $5 each for machines 2-5, people.
Yes, you can buy the single license package and install it on a ton of machines, because Apple doesn't implement any sort of activation or duplicate serial number detection feature... yet. But you're without honor if you do this. Apple, Microsoft, Adobe, and every other quality software company out there spends a huge amount of time and money to create these products for us to use and hopefully enjoy. The very least you can do is to not be a jerk and rip them off. There's very little difference between buying a single license package and installing it on multiple machines and just pirating the whole thing.