Best quiet heatsink for LGA775 small tower

Hi,

Looking for advice for the quietest air cooling CPU fan for my HTPC.

It's a Core 2 Duo E6600 in an ASRock 775Dual-VSTA mobo in a small tower. This mobo was one of those that came out when PCI-E video cards were just becoming popular, so it has both PCIE and VGA video slots. Aside from that 'bonus', it is absolutely awful at overclocking or any real tweaking. But not really needed for my HTPC, which is used as a DVR, putting out 720 video, and websurfing. The CPU fan is definitely the loudest component of the system. I have an extremely old-school NVidia 5200 FX fanless video card and a Seasonic PSU.

I had been using the stock fan, but it seems to have grown louder over the past year or so. Aside from cleaning the fan, which may have modest sound improvements, what suggestions do you have for an aftermarket CPU cooler?

I'd prefer something that doesn't need a backplate mount and is <$50. It's not in a full tower, so a huge behemoth heatsink probably won't fit very well.

Some review articles from way back suggest maybe the Arctic Alpine 7 Pro. There are several versions of that at this point, as well as a GT and 11 model, and I'm not really sure what the differences are between them. They run ~$15. But it didn't seem they were much quieter than stock. Another was the Scythe Shuriken, now in rev B.