My husband thought my wheels and also my tires might be a big chunk of the weight -- he's going to swap our wheels on the next ride to see if I can feel a difference. He is very excited that I had fun yesterday so I think I might be getting mountain bike components for Christmas. Awesome.

Steel: his mountain bike is a relatively ancient steel Bianchi that he is never tempted to replace because it is so much lighter than, for instance, my bike. It was pretty low-end, I think, when he bought it ten years ago, but he just keeps upgrading it and I sure couldn't find anything as nice that I could afford when I was looking. (He offered to build up this frame for me but it doesn't come in my size.)

Thanks for the feedback ... I think what I will do is keep riding this one for the next couple of months and get a better feel for what I would like to upgrade/replace, and if it seems like what I want to upgrade and replace immediately is going to be in the $500 range, then I will buy a new bike. Because at least around here, a used/excellent condition Rockhopper can be sold for almost what you paid for it.