Be interested to hear your results. My own Noctua's are behaving quite nicely on a radiator, and I'm pretty anal-retentive about noise, so I'm not sure what's wrong with yours.
In this case, I'd probably point you towards the Scythe S-Flex fans. The E-series would match closest in rpms, while the F-series would be a little faster (and louder). Great bearings, long-life, and solid radiator performance. Easy to order online, of course, but if you find yourself heading into the GTA, I've noticed that Canada Computers stores have started stocking them as well.
__________________ QX9650 @ 4.038GHz (425x9.5) | Asus Formula Maximus | GTX280 (777/1620/1404) | Mushkin XP2-8000 Redline 2x2GB
Q6600 @ 3.6GHz (400x9) | MSI P35 Platinum | 8800GTS 640MB (700/900) | Mushkin EM2-6400 2x2GB
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