A class really helped Belle...she was about the same way with other dogs, and learned to focus on me rather than on them. I started classes with her when she was 3 years old, and if you have a good instructor, you should make great progress with her.

Unfortunately, Belle now only associates getting along with other dogs with an indoor environment or with a fenced-in environment, since the class was in an indoor facility, and I have had her to play at a fenced-in agility course nearby. She still acts up as soon as another dog is visible if we're out walking up the road. If I don't catch her in time to say 'leave it' (which is my command for 'ignore whatever you're paying attention to and focus on me'), then I just ignore the behavior and keep walking...and keep an eye on the other dog just in case, since we don't have a leash law, and most people leave them loose. Eventually, she focuses back on me and walking, and sniffing whatever is interesting, etc. It's been said many times on these boards that any attention whatsoever to a behavior (whether it's positive or negative attention) will reinforce the behavior. As long as it's not going to physically hurt them, don't intervene.

I also invested in a micro-prong collar for training purposes (it has rounded ends on the prongs so that it can't break skin, and you should be very, very gentle in the correction tug if you have to use one...I actually put it on my own neck to see if it hurt, and it didn't, just uncomfortable). This will save your shoulder/arm if your dog lunges unexpectedly, and when that behavior is trained out of her, you can usually switch back to a normal collar for walking, etc.

Good luck!