Weightlifting to get in shape

Hello all,

I'm a male age 36, and I am not in great shape. I'm about 5'8" and I'm about 260, and I've been trying to steadily loose weight. I've finally gone back to exercising (had a physical, doctor said it was fine) and for the past 2 months I have been using my treadmill about 3-4 times a week. I try to do about 25 minutes an evening, and try to push myself (I do a 3 degree incline, and work myself up to about 3.5mph) - I get a good workout and feel good after it. I have noticed that my belt size seems to have gone down a notch, though I haven't been weighing myself (Yeah, fear that I'm not doing it right).

I have added weights to my regimen, though not any form of real high intensity weight lifting. I've been doing bench presses - about 5 sets of 10 reps each very light weight, arm curls with hand weights 2 sets 10 each. I also do situps (about 25 at this point, sorry can't yet do more my stomach gets too tight!)

Is this form of weightlifting beneficial? I do feel it in my arms the next day, so I'm sure it can't be useless. Is high reps with light weight a good thing, or am I wasting my time?

weight lifting is beneficial in toning up and gaining muscle. Though, if you are wanting to lose weight as well as fat, then it is bad because muscle weighs more than fat.