You really need to get an after market fan. You won't get very far with the stock fan to see much improvement.
If money is tight, then the Cooler Master Hyper 212+ is an excellent purchase at $30. I use it on my X3 which I've overclocked to 3.61 ghz (x18) and I've also unlocked the 4th core. This required me raising my CPU voltage to 1.5, but my temps stay around 33c idle and 47c full load.
Yes you should always use a thermal lube whether you OC or not. And Besides the cost the Cooler Master Hyper 212 is an excellent choice all around. BUT it is tall, not that you would have a problem with your haf932.
But seeing as it is the same as the 955 I'm thinking you can set it at 3.8 ghz safely (19.00x clocK). Just test it with AMD overdrive and stress test it before you permantely set it in the bios.
On mine I set it to the 3.8 ghz as above and I idle at 28-29 (lowest so far) and a max load of 40-41c.