Are you able to use a flash?

Take a shot, look at the lcd, adjust the exposure, till it looks decent.
Or even better, turn on the histogram to see exactly what your exposures
look like.

Aperture priority mode wide open f/4-5.6 and keep an eye on the shutter
speed to be sure it's hand holdable and if not lean on the wall or
increase the ISO. Put the metering mode in whatever is most center
weighted, spot meter if available. Put it in manual mode if metering is
a problem, the aperture is already set, just dial the shutter speed in.

My immediate guess is that those lenses are too slow to work well for
this application.  Yes, I see the "IS".  I'm sure IS is great -- but
my experience with this kind of club shoot is that the *subject
motion* is the limiting factor, and IS doesn't help a bit with that.

My secondary suggestion is -- instead of looking for "settings" advice
from people who've never been in the club in question and haven't seen
the lighting, *use the power of digital*.  Take a few sample pictures
and look at them *closely*.  Zoom in.  Check sharpness and detail on
the face.  Check the exposure histogram, see what's being cut off.
Then adjust from there.

Good luck!

    IANApro, but I've taken a few pictures at concerts, some of which
have come out pretty decently.  I think everything that's already been
said is pretty sensible.  I'd just like to add:

- You may not be able to get technically great photographs (high ISO,
performer moving, weird lighting).  So don't fight it, use it!  Use the
weird colors, let the performer blur a little, make it atmospheric.  One
of my concert photos I like, of a drummer, is not very good - the
drummer is overexposed and everything else is dark, he's motion-blurred
and the focus isn't great anyway - but I like it because it captures the
energy and motion of the moment, conveying the drummer's movement and
emphasizing his isolation and complete absorption in what he's doing.
Another one shows one performer silhouetted against another: the
non-silhouetted one is a little too orangy-red and the background a
little too blue, but if I "correct" the picture to bring out the
foreground performer and make the colors more accurate, it loses all its
drama.

-Be aware that the lights may be at bad angles, shining right into your
camera, so take this into account when thinking about exposure.  

-If you're not doing it already, shoot in raw format to maximize your
ability to correct things like white balance.

-Try to explore beforehand to see where you can go, what kind of angles
you can get, and what blocking issues there will be.  Consider what the
background of your shots is going to be.  I have one that's pretty good,
with the performers in the bright yellowish stage lights and the
audience in the background in blue shadow - except for one annoying guy
standing forward far enough to be in the same lighting as the stage!