If I just cut out all sugars, starches (including bananas), and grains

and

Eat
Meats, Seafood, Cheese, fats/oils, vegetables, fruit, nuts
and
exercise 3 days per week: 2 strength training, 1 cardio

Do you think I can lose 30lbs? How long do you think it will take?

Or will this just help me maintain where I am?

Well, that's basically what I am doing and 9 lbs are gone so far, so I think there's something to it. I don't eat fruit, though, and I stick to the veggies from the Atkins book - no corn, carrots, etc. I haven't added any exercise yet, so that should speed things up a bit for you.
I am loosely basing my personal plan on Atkins, so it would be helpful to read the book and get an idea of where to start and then do what fits with your life, because everyone is different. Best of luck to you!

Slimmindy,
Once I got down near my goal weight the first time on Atkins, I did basically what you and Mokki are saying. Cut out the sugars, etc, I didn't eat fruit, except bananas (cause I love them), and was able to maintain my weight for a long time, about 4 years. I did eat bread and pasta during that timeframe in moderation, but no regular sugar, no candy bars, etc.

This year I got really lax with it and ate a lot of stuff I shouldn't have and gained 20 pounds back pretty quick. The thing to keep in mind is that it probably work well, but you have to consider it a change for life or you will gain it back.

I think that it depends a great deal on how well such a diet satisfies your appetite and, consequently, how many calories you might be prone to eat on such a diet compared to the amount that you were eating prior to removing grains, sugars, etc. I would be cautious/aware of fruit, cheese, and nut consumption.

Some people find that fruits increase their appetite, while others find them very filling and satisfying. One of my intro to nutrition courses suggested giving fruit as a way of increasing appetite. Our reactions to foods are often quite individual.

It is very easy to overeat nuts (20 macadamia nuts--about 1/2 cup--have around 400 calories). I know that I, for one, need to be cautious about nuts, as I find it WAY too easy to eat a cup or more of them in one day. Oops!

Cheese/dairy, like all other food sensitivities, can also impede weight loss if a person is sensitive to it. Cheese can also be very constipating. Studies have shown that regular bowel movements aid weight loss.

The exercise sounds like a great idea, too. I know that I always feel that I look my best when I exercise regularly. I definitely find that my diet affects my weight, but exercise is what really makes it or breaks it for me.

Good luck!