[PrincessDiana]

First off, have them meet at a neutral location. I would take them for a walk around your neighborhood or perhaps go to a nearby dog park. It's important that your old dog does not feel threatened. Afterwards, if they seem to do okay, transition to your home. It is important that you make sure your existing dog knows that you are not replacing him. Greet him first, play with him first, feed him first. Make a special effort to spend alone time with him.

It's important that you know that they will not get along right off the bat. There will be fights, and most likely they will be pretty nasty. When we first got Maggie, she attacked Franklin any chance she got. It was so bad that I considered giving her back. We had to keep them totally separate for two weeks. The only contact they had was very supervised and no longer than 3 or so minutes.

Now, while they will fight, it's absolutely necessary that you do not interfere. Unless of course you seriously think that they are injuring each other. Most of the time, it sounds a lot worse than it is. Dogs are pack animals and they need to sort out who will be dominant. Dogs are much more comfortable when they know their place. It makes their life a lot less confusing and stressful. Your intervention will only make it more confusing. You may find that your new dog is the alpha dog. If this is so, you have to go with it. This dog gets the better bed, better toys, first feeding... all after YOU of course. You have to remain the pack leader, then comes the alpha dog, then all the others. They need to be able to look to you and get direction.

Sorry this is so long! I got carried away. I hope I answered some of your questions, if you have any more.. feel free to ask!