I'd say just try a google search for the machine your looking at or just search "cardio exercises" there's a lot out there. I don't know any books off the top of my head, sorry I can't be more help.

One thing I do personally is interval training. I'll walk fast for 3 min, jog for 1, walk for 3, etc. Supposedly it burns more fat, I can see why though, it keeps my heart rate up :)

You should check out StrongLifts.com.

It's by far the best website I've found for someone who wants to be fit. It's very thorough and honest about what works and what doesn't.

Good luck!

Women's Health Magazine and website has a monthly spotlight of different gym exercises. Prevention Magazine also has a monthly workout routine.

If you can afford to do the personal trainer, it might be worth it to do it once. You can sit down with them, they can evaluate you, help you figure out the best routine for you. I've done this and found it very helpful.

Shape.com

Try www.exercisetv.tv

Are you just looking for advice on cardio machines?  Weight lifting is a very important component to any complete fitness program.  There are a couple of books that come to mind to give you ideas and routines for lifting weights at the gym.  Jillian Michael's "Making the Cut" is an excellent book which also lays out a good diet plan to drop 20# or less, but you could ignore that and look through the exercises she gives.  Another fabulous book that many people love and get good results with is "New Rules of Lifting."  I believe there is one specifically for women called (curiously enough, LOL) "New Rules Of Lifting for Women."  David Kirsch also has a couple of books out that might be helpful to you.  Their names escape me, but if you search here or at Amazon, you'll be sure to find them.  Good luck to you and kudos for wanting to stay fit and healthy!