I have been losing weight steadily up until about a month ago, I hit a plateau. I have been going an hour on the eliptical a day. Is this too much, or should I use both the eliptical and the treadmill? I'm wondering which machine will help me bust out of my plateau. Should I increase the resistance, or what should I do to get out of this rut?

try the treadmill. Add some variety. New stress elicits a response by the body. Also, double check the diet. As you lose weight, that needs to be considered as well.

Definitely check the diet. As your weight decreased, your calorie needs decrease as well. Many people forget that little fact and continue eating the same number of calories as they did when they were heavier. The less you weigh, the fewer calories your body needs for maitainance.
As far as your workout, you should "mix it up". Do different machines, different intensity, different order in which you do your exercise, different exercise(s), vary the amount time, etc.