Hour of treadmill vs. 45min. treadmill & 15min. weights

Ok so it's a new year and I am motivated to lose 20 of the 30lbs. that I gained back since my surgery in 2006.  I remember that when I had my surgery the surgeon said to walk an hour everyday and the weight will come off.  The last time I joined the gym, I walked on the treadmill for 45 min. and did 15 min. weights and seemed to lose inches but gained lbs. because muscle weighs more than fat.  Is it better to do an hour on the treadmill and no weights or 45 min. on the treadmill and 15 min. of weights?  My plan is to lose the lbs. then tone because I want the scale to go down in number.  Any suggestions would be greatly appreciated!!

If I had 1 hour to do both, I would do 30 and 30 on most days.  Some days I might do an hour on the TM but most days, I'd split it.  Muscle burns more calories at rest so when you are doing absolutely nothing, you will be burning calories if you add muscle.  30 minutes on the mill is enough to get some good cardio in.  If you have race goals in mind, that may change but for overall fitness, spliting it would be fine.

I did almost entirely cardio in the beginning and I regret that decision.  I lost so much strength in my upper body.  It is certainly harder to gain it back than it would have been to keep it.

I would recommend either 30/30 or 45/15 and make sure you mix up the weights it you only have a few minutes.  Rotate target areas.  Today 45 minutes on the TM and 15 minutes doing arms, tomorrow 45 minutes on TM and 15 minutes doing chest or abdominals or back.  Something like that.  Give yourself a recover day, where all you do is rest.
Also you should have a lower body/legs day, so you might not want to run on that day.

Everyone is different and different trainers will give different advice.
Mine started me out doing really light weights 3 sets of 20 reps.  The weight were so light at first that I thought it wasn't doing anything, but by the time you have lifted it 60 times it starts to get heavy.  When you can do that without feeling exhausted, make a slight increase in the weights.  This should geave you the strong lean muscle mass without bulking you up.

Good luck with your routine!

Scott