Janie1234: I've heard great things about accupuncture for low back pain. A good accupuncturist will tell you, up front, that if the treatment doesn't help significantly by the 3rd session, it probably will not work. As far as the chiropractor, depending on your specific back issues, you may only get a "manipulation" and probably not the "back cracking" you are thinking. I had one chiropractor that would just gently massage my low back area. That same chiropractor also did accupunture. You definitely want to research & interview for a chiro. Like people have said, there are good ones and bad ones.
I have tried both chiropractic care and accupunture in the past year. Neither of them helped me(or hurt me) with my lower back issues. It didn't make my symptoms better or worse, just didn't do anything. I will mention that even though I have low back problems (spinal stenosis & spondylolisthesis), I do not have any pain in my back; it's all in my right hip, leg, and calf. Anyway, what has helped are 3 cortisone epidural injections for my back(to get the inflammation down), 2 bursitis shots for my hip, physical therapy with exercises specifically to strengthen my core, and tons of lower body stretching. Recently, I added pilates to the mix, and wow, has that helped!
Whatever treatment route you seek remember to listen to your body, voice your concerns, ask questions, bring a note pad to take notes, bring a list of all the symptoms you have, and trust your instincts. Gee, can you tell I've been to a doctor, chiro, and PT or 2 or 3??