I've done a fair share of "music photography", both concert stuff and studio/portrait stuff.
I shoot with two bodies: a Canon 5D and a Canon 40D. I use the 24-70 f/2.8L on the 5D and the 70-200mm f/2.8L on the 40D.
I'm going to guess that you're probably going to be shooting in a "club" as opposed to a "concert venue".
Shooting in clubs has some unique challenges. Generally speaking, the lighting sucks. For whatever reason, many bands these days seem to think the red lighting is cool. Well, it may be, and it may look cool to the naked eye, but it presents an absolutely horrible condition in which to shoot. The only color that's worse is magenta. If a band is using only (or primarily) red lighting, I usually won't shoot.
In such instances, you can try talking to whoever's running the lights. Oftentimes, this guy is hired by the house and not the band and, as such, has a lot more leeway in how he chooses to light a band. I've made requests for more greens, whites and blues and, sometimes, they oblige. Often, however, they don't. It's hit or miss. I've also had lighting guys who agree to do it, and then seemingly suffer a stroke and completely forget they ever even had the conversation.
Assuming the lighting guy grants your wishes, well, now you've got another challenge to deal with, that being the proximity of the lights to the stage. The ceiling (where the light bar usually is) isn't that far from the stage, so the lights easily blow out the performers.
When I first started doing this, I would shoot a few frames in "P" mode, just to see what settings the camera wanted to see. I would then switch to Manual, set my camera to the settings in the "P" mode shot, and adjust from there. Nowadays, for a shoot at an actual concert venue, I can pretty much nail my settings from the get-go. In a bar or club, though, all bets are off.
Generally speaking, I shoot at an ISO of 1600 on the 40D and either 1000 or 1250 on the 5D. I'll set my white balance to tungsten. For a club shoot, my aperture will be at f/2.8. For a well lit concert venue, I've shot as high as f/8. Shutter speed is where you'll live or die. For clubs, it's sometimes difficult to get much higher than 1/60 of a second. Well, that's just not fast enough, and that's where the frustration sets in. You can freeze the action, but it'll be dark.
I've shot concerts in both raw and jpeg. Raw is the go-to in those dimply lit clubs. A well lit concert venue? I normally shoot jpeg for those.
I will take exception to something fjrabon said about gear. You don't need the latest and greatest equipment. Yes, an f/2.8 lens is almost a "must have", and a body that works well ay high ISO's is nice, but I shot concerts with a Canon 20D for a long time, and photos taken with that body have made me a
lot of money. Okay, it may not have worked as well as my current bodies in low-light, but it still worked, and it worked well. A little tweaking in a noise-reduction program did the trick.
Here's a shot taken with the 5D:
John Rzeznik - Goo Goo Dolls
And the 40D:
Taylor Swift
And the 20D:
Tommy Shaw - Styx
Obviously, those were all taken under pretty damn good lighting conditions, but I wanted to show shots from three different bodies. Just because a camera is old doesn't mean it won't get the job done. I wouldn't hesitate to shoot a show with a 20D. Sure, it's several years old, but it's still a capable camera.
I also have to disagree with the idea that a great camera in the hands of a hack will garner better results than a "lesser" camera in the hands of a pro. Put Mario Andretti behind the wheel of an 88' Honda Civic, and he'll drive the wheels off it. Put my neighbor behind the wheel of a Ferrari 458, and he'll trash it before he gets out of his driveway. Knowledge and proficiency, I believe, are more important and, as a result, have more of an impact on the final image...