If you want to shoot low light, use a low light lens. Bad news though, they don't come cheap! Compare your photo with this:
This was shot using a Canon 70-200mm f/2.8 L series lens at 1,000 ISO. The bad news? This lens costs $2,000.00 new!
My EXIF data says this:
Camera Canon EOS 40D
Exposure 0.001 sec (1/1000)
Aperture f/2.8
Focal Length 200 mm
ISO Speed 1000
Exposure Bias 0 EV
Flash Off, Did not fire
Your EXIF data says this:
# Exposure Time (1 / Shutter Speed) = 10/300 second ===> 1/30 second ===> 0.03333 second
# Lens F-Number / F-Stop = 56/10 ===> ƒ/5.6
# ISO Speed Ratings = 1600
# Original Date/Time = 2009:12:17 18:30:08
# Flash = Flash did not fire
The huge difference here is the shutter speed. I was shooting 1/1000 while you were shooting 1/30. 1/30 at a long focal length with no IS just about guarantees movement will be an issue. If you would have been able to drop to f/2.8 odds are you would have been shooting above 1/60 which would be better suited for the photo. I had more light from the stage lights than you did from the flat florescents overhead. You wouldn't have got 1/1000, but you definitely would have got a better photo.
If it is not something you really care all that much about, I wouldn't spend the money on the lens. But if you really want quality images it requires a quality lens. Think about that as you purchase future lenses.