40 degrees is actually very cool for that chip. I'm running a decently rated coolermaster (made for 2100+) on a 1800+ chip, and my cpu usually hangs around 48-53 degrees, and that's with a thin and evenly applied layer of arctic silver III.
If you are really concerned, you could try one of the current monster coolers like an alpha or globalwin, but I doubt you'd get much lower than your current temps. There's also peltiers and water cooling, but that's getting rather extreme.
Nite_Hawk