"Powered treadmills confuse me"
I felt the same way, so I bought a manual treadmill. They're hard to find and the biggest one I could find was a 48"x16" belt, which is really too small for me, but was fine for my wife. It provided a good workout since the user had to supply all the energy. Note that I said "provided", not "provides". I ended up returning it. The problem with a manual treadmill is that you have to hang with your hands the whole time. If you let go, then you don't have anything to push against and will just walk off the front of the belt. It's funny how sometimes things like that aren't obvious before hand! Having to hang on all the time was hard on my back and made my hands start to go numb after about 20 minutes.
So, now I have a motorized treadmill. It's a 50"x18" belt, so it fits me much better. It has a power incline and a lot of fancy features to make the "walk" or "run" more interesting by having pre-programmed "courses" and iFIT technology so it can be hooked to a computer or TV so you actually see the course. We bought it for winter use when it's too cold out to walk or run. We've only had it a week and haven't even tried it yet because I'm just getting over being sick and so is my wife. We'll see how it works out in the long run (pun intended!).
As for losing weight, I lost over 25lbs by cutting way back on eating and eliminating sweets altogether, and swimming for 30 minutes as hard and fast as I could 3 times a week. I lost 5lbs a month this way. Now that I'm down to the weight I should be, I just need to keep from regaining it! I plan to only swim once or twice a week and mix that with the treadmill or actual walking or running, depending on the weather. The key to losing weight is to BOTH exercise AND diet. If you just diet, your body will lower it's metabolism and try to shut down to conserve energy, so you won't lose weight very fast. If you just exercise, you won't burn fat, you'll just burn the food you eat. A weight machine or Bowflex type machine is mostly for building muscle, not for losing fat. Good luck!