Please ignore the person who was talking about vegetarian kids having learning disabilities. Boy, what a crock. No wonder the mother got mad at her - ignorance isn't always bliss.
I have been vegetarian for 10 years, and my husband (by the way, he has an MBA from a top 10 school and graduated at the top of his class) was raised vegetarian. It is very important to make sure that your kids are getting enough iron and protein, but recent studies have shown that the protein from beans is healthier than the protein in meats (and you can eat less to get it). Soy is higher in estrogen, although there have been no conclusive studies done by esteemed science organizations that have shown it to be problematic in moderation (and people in cultures where soy is more routinely eaten, such as in Japan, have longer lifespans). A balanced diet is always best - don't overload on any one thing.
I highly recommend Morningstar groundbeef substitutes and bacon, and Quorn chicken substitutes. These two products have allowed me to make most of my mother's old recipes meatless, which is great for our family! Also, try Yves lunch-meat substitutes, and Amy's Vegetarian Burgers. Nothing tastes just like the real thing, but some of them come close. But expect to occasionally try something and find out it's gross - we've all been there, and your tastes will also change as you get farther away from meat-eating. Also, check out the magazine The Vegetarian Times. It has lots of great recipes and ideas for vegetarians.
You mentioned soy products (soy milk, yogurt). I am not a vegan, and so I tend to stay away from those. If you are planning to become vegan and not just vegetarian, I'm afraid I can't help you (but wish you luck), but depending on your reasons for becoming vegetarian, different dairy products may work for you. If you are doing it for health reasons, try eating organic dairy products such as Horizon Milk or Stoneyfield Farms yogurt. If you are doing it for the love of animals, buy local and stay away from factory-farms (Whole Foods or Trader Joe's often has at least one local milk/cheese in their dairy section).
One final comment, although it is just my opinion and you don't have to listen to me. First, I would start slow. Maybe cut beef out of your diets, and continue to eat chicken and fish for a couple of months, and then ease out of the next one. Then your kids won't have to deal with their entire diet changing all at once, which could be stressful.
Second, I would be careful about forcing a vegetarian lifestyle on your husband and children. I don't mean you shouldn't switch over (I don't cook any meat in my kitchen - ever), but if you go out to eat and your kids want a hamburger or something, you might consider being flexible. In my own personal experience, people (even meat-eaters) are a lot more open to vegetarian options if they don't feel forced or resentful. Plus, kids love to rebel, so if this issue is important to you, you may not want to make it one they feel a need to rebel against. But once again, just in my experience. I wish you lots of luck, and feel free to send me a private message if you have any further questions.