Some of the comments on this thread are just ignorant... Sorry. I'm normally not so outspoken, but free weights not being "safe?"
Here's a question for you. Is your body designed to work in isolation? When you are chasing kids, carrying groceries, working in the garden, do you isolate any of your muscles?
Your body does not move in fixed planes. I'll tell you what's unsafe... Training on MACHINES!
If you isolate your parts, they don't "learn" how to fire in harmony with the other body parts that they are technically designed to work with.
Most injuries are caused in the "real world" in the deceleration phase of movement. One great way to enhance this is to use machines. Your muscles proprioceptively protect your joints, but if you don't train them to do that, they "forget."
Not only that, when you recruit more muscle you rev up your metabolism. If you spend your entire day on your ass (like most people do today), why in God's name would you go to a gym and sit down? Not only are you recruiting less muscle, you are creating strength and flexibility imbalances, and your movement will have no transfer to the real life movements you do from day to day.
I will go ahead and go on the record and say that the machine is the single worst thing to ever happen to the fitness industry. In a word, they suck!
All that being said, I really do like FreeMotion equipment because it specifically does not use fixed planes. It's not my preference, but as far as machines go it is better than anything else out there.