I am not an expert on weight lifting. But if you pm Meg or Mel from Maintenance or weight lifting forum they are full of great advice. Books I would recomment for beginners or anyone. The eat clean diet workout by Tosca Reno, Burn the Fat, Feed the Muscle(online book) by Tom Venuto, more of a bodybuilders nutrition book, Precision nutrition by Dr. John Berardi, also more of a nutrition book. The new rules of weight lifting for women by Lou Schuler.
As far as aches and pains. I have many less aches and pains since I started lifting than before. I also wish I didn't wait till I had lost some weight before starting. If you put on weight, the weight is water retention and only temporary. It takes a long time to put on a pound of muscle versus a pound of fat. At least that is my experience.

I'm down 13 pounds and saw a pretty quick difference in my pants, none at all on top. (Which is the opposite of what usually happens, in the past I have lost from up top and only later from the bottom.)

I find that noticing a difference is really dependent on the clothes. I don't notice a particular difference when I put on my elastic waist pants, I do in some pants I bought that have zippers and no elasticity.

On the "why put on muscle weight" issue, hey, the number on the scale is only a standin for the way I want my body to look and feel. Would you really care if you weighed the same and had a 24" waist? Muscle may be heavier but it does speed up your metabolism (muscle burns calories, fat does not) and also looks a whole lot nicer on the body!

Muscle isn't heavier, per se. A pound of muscle weighs exactly what a pound of fat does. The truly great thing about muscle (and why people say it's heavier) is that a pound of muscle takes up considerably less space than a pound of fat. I'd start weight training now. If you're using proper form and not starting out too heavy, it will actually increase your joint strength, not cause problems.

Good luck!

Oh yeah, it took me around 30 lbs before I started noticing a big difference in my clothes. But, the lighter I got the fewer lbs it took to drop a pants size.

Thanks everyone for all the great information and tips. I think I will start to incorporate a strength program. My knees and back are so bad and that's the real reason I wanted to lose weight (But who are we kidding. Looking great in jeans is a good motivator too!)

This place is the best!