Right now, if you are working on fuerte you only have to roslaunch openni_launch openni.launch this will launch all the nodes related to the kinect. If everything is correct you should se the topics with a rostopic list.
/camera/rgb/camera_info
/camera/rgb/image_raw
... A lot more.
You can be sure you are receiving info by typing in the terminal rostopic echo /camera/rgb/image_raw a lot of numbers will full your screen in a few secs.
Open Rviz add a display for the topic you want to display. And you should see the data if everything is correct.