Not that I can offer any advice, but here are a few of my photos from my cousin's outdoor night concert a few weeks ago. http://www.pbase.com/nhmom/mikes_concert
You should be able to see from the data below the pics what my settings were. I had only taken the Tamron 70-300, Pentax 18-55 and 50mm/1.4.
Needless to say, it was difficult to get good shots. Between the low light, constant movement and rain we had, I wasn't real successful. It wasn't until nearly the end of hte concert that we realized our "VIP aftershow" passes meant we could go backstage during the whole show. The park rangers kept telling us it meant we could only go back after the show. But, we have the memories of our night.