yep...i think the fan that comes with it is pretty quiet, something not associated with thermaltake for the most part i guess. but when i listened to the fan alone it seemed to be making little clicking sounds so i switched it out with a coolermaster 80mm rifle-bearing fan from the clearance section at svc. the thermaltake fan seems a nipple's worth quieter than the coolermaster though. so i was kinda surprised considering how lots of people say the coolermaster is quiet. oh btw the thermaltake fan is 20mm thick. but the other reason i switched it out was because the thermaltake fan had a tapered shape to it..i guess it was because of the 90mm blades on a 80mm frame..but i felt like there was a lot of air rebounding off the tapered walls of the frame, if that makes any sense.
here is a rough sketch of what i mean.
bottom line though...if you have patience then just order the xp90 or something from svc/jabtech. but if you want something new now without a huge price difference between online and compusa, then you could consider this. i don't think it's guaranteed to bring your temps down, but i think it'll keep it the same or lower it a few degrees without the noise of the stock hsf. for me personally, i've gotten about 4 degrees C lower on average.