By doing 100 sit ups per day how long will it take to tone up my stomach?

I have a reasonably slim/flat stomach anyway, but it's not quite as toned as I want it to be. I'm cutting down on calories by at least 400-500 per day, so i'm eating approx. 1000-1200 calories per day. By doing 100 sit ups and some other workouts (following the Rosemary Conley workout) how long will it take for me to get a flatter stomach? Also, what other exercises can I do to achieve this? Also, what are some other exercises which I can do to help slim down my legs? I would run, but I currently am not allowed to due to a ripped cartilage in my knee and I'm allowed to start again in 2 months. So, are there any exercises I can do which will tone, but not 'bulk up' by leg muscle, as I wish to slim them down to size 6 or 8 (currently a 10) Thank you!