What software do you use to convert your raw files? The files from these old DSLRs benefit more than most from a really good raw converter. It might be worth your time to try out Photo Ninja or Capture one. These applications get more DR and lower noise levels than most at high ISO values.
What lenses do you use? Low light calls for fast primes or the f/1.8 zooms from Sigma shot more or less wide open.
I don't know if I did this right, but here goes.