GCWB:
1. While your lens, is rubbish, you really should not have much noise if you shoot at 1600/2500 ISO. Most of the images are resized for web format, which does eliminate much problems. I have friends who shoot with the 7D in clubs and produce great images. Alot of your problems may be directed to how you process your RAW files. Can you post some photos you have taken, then I can give you better feedback.
2. Diffuse your light more. Get a Lumiquest big bounce. That's my moneymaker. That and a second flash.
3. Find your shooting style and learn to work with it. 99% of my shots are at f/4.5 f.5.6. I use a old 28mm canon prime, non USM, from 1987...yes..1987. The lens gets the job done.
If you go to www.nullochvoid.com
you can see the shots I have taken with it.
There is a shot at 2500iso...f/4.5 with a 1/15th shutter speed. With my same, "crap", lens. I plan on upgrading to the USM version sometime, but I am in no rush.
It's all about using proper lighting.