It depends on who the contracting company is and how desperate they are to place employees. The last time I was a contractor they didn't offer me paid training, paid vacation or medical coverage. So I just asked them for it.
They didn't even argue and gave me everything I asked for. I guess if they had 40 people standing in line, behind me, with the same experience, it probably would have been a different story. But I always was pretty confident.
In a lot of ways I preferred being a contractor. In most cases you didn't have to put up with quite as much bs as company employees.