If you're a total newbie, maybe get 1 set of 5lb dumbells and 1 set of 8 lb. Do a few bicep curls or something in the store. If you get really fatigued with the 5's - get 2, 3 lb ones instead, and 2, 5lb ones.

www.exrx.net and www.stumptuous.com have good info on building a weight routine, with photos.

Don't give up your cardio though. It does burn fit and is good for you, as well.

When starting an exercise routine, in my humble opinion what is important is consistency and trying to find something you enjoy so that you stick with it. Don't feel you are not doing anything worthwhile if you're not as gung ho as other people. Baby steps!

Listen to your body, and try to be honest about whether you're really challenging yourself.

Just try to get moving as much as you can. Dance around the house, go for a walk, a bike ride, play with the kid's hulahoop - whatever. Try to have fun!

Good luck.