The xbox it is quite easy to do but the 360 is another matter, swapping the ones in the 360 would probably cause more harm than good.
I've seen a site with a vid about the Talismoon if that's the one with twin fans & green lights. Looked good & the figures were not bad but voiding my warranty is a no no even though i can only fault my 360 on Noise levels.
It's the DVD drive that creates most of the noise anyway. At least, it is on mine..