processor cooling

I currently have a 1.33 ghz amd, not overclocked. on an msi pro-r mobo, 256 ddr ram 266 fsb. I have a thermoengine xtreme with a 7k fan on it right now. the processor is running at 40 C right now. i want to get it cooler because i would like to overclock it to 1.4 or 1.5. do you all recommend just getting a new HSF and in that case, which one should i get?????

swiftech or sk6

ok
thanks man
i think i will go with the sk6
the swiftecs are hella expensive

dont forget the arctic silver 2 thermal compound