I have a SLK-947U + 19dB 80mm Papst on my Barton 2500+. The cpu is overclocked to 2.35GHz at the moment, but I'm still searching for the best OC/Vcore/temperature combination. I have everything in an Antec Sonata, the case closed and 2x 120mm case fans. The cpu temp is 46'C idle at 1.65Vcore, and about 50'C under load.
Sounds about right doesn't it?