Sime will probably have better advice (he's done bigger shows than me)
but i tend to use 1600, with a 50mm f1.8 and then depending on how good the lighting is depends on the shutter speed
These were done on a Canon Rebel/300d - i've not had a chance to try out my new 5d mkii yet with gig photos...
Parry's Photos :: 2009-11-25 - The Indelicates, London
Parry's Photos :: 2009-10-21 - 18 Carat Love Affair
Parry's Photos :: 2009-09-03 - Tim Ten Yen
Parry's Photos :: 2009-09-03 - Jim Bob & Chris T-T