Firstly well done on the 16lbs
! The short answer to your question is that I think you have to do quite a lot of cardio to lose weight but it is probably not the best way to approach exrercising-as in purely as a way of losing weight.
You need to see it as more all round fitness and toning and certainly a long term habit rather than a quick fix. Really important is that you must include resistance training to build up muscle...and don't worry, this does not mean getting bulky, it is v v hard to get to look like a bodybuilder! Weight training will have the two-fold effect of increasing your metabolic rate (muscle burns more calories than fat, even in resting state, so long term, you will lose weight gradually, if your diet is the same ie you aren't over eating) and muscle is denser and will look smaller than fat-so you may be the same weight as someone with a greater weight to muscle ratio but you will probably be one or more dress sizes smaller and look more toned, in which case weight is irrelevant no?
What you are doing sounds like a great start, running 4 times a week will be great for burning calories but try and build up to 40 mins+ and also introduce interval training once or twice a week, so warm up with a jog for 10 mins then for say 10 mins you sprint fast for minute then walk for a minute to recover. You can play around with the length of the intervals as you get fitter. End with a gentle jog for 5 mins. Training this way is supposed to burn fat much more than steady state cardio and will definitely speed up improvements in your fitness.
On Wii days do some training, pref with weights (start with about 4kg dumbells and see how you go, increase so that you struggle to lift the last few reps in a set of say 12. (do shoulder press, chest press, squats, lunges) and do some press ups and tricep dips. Then if you can squeeze in a bit of cardio, skipping is fantastic, do that in between exercises.
If you stick to this and eat sensibly I bet you will see quite a big difference in your body in a few weeks, ignore the scales and judge by clothes and how you feel. 