wow.. something I actually know about.
I think your from the U.S., so you might find a better deal somewhere else.. I'm mostly linking to show some specific's of what to look for.
First.. if you can, switch the 80mm fans for 120mm fans.. big fans spinning slower move the same amount of air, but are much quieter.
Here's a link to a good online company that ships to both Canada & US. NewEgg etc might be just a good for the US
NCIX USAt least at NCIX, all the fans have a db rating, and Cubic Foot/Minute rating.
You want to use the biggest, slowest fans you can fit in your case, and only use enough fans to keep decent airflow.. for a HTPC you won't need overclocking etc.
Noctua and Scythe are two great brands of very quiet fans.
Also.. for the video card.. try and find a passively cooled solution.. (I recently saw a passively cooled
9600GT , which would be overkill for a HTPC). A Passive video card with a 120mm case fan nearby at even 20 db is going to basically inaudible.
From what I've seen.. the best fans are the
Noctua (80mm fan).. from the couple of the pictures of the case, your probably stuck with 80mm fans.. It looks like airflow in the front of the case might be pretty restricted as well
The AMD x2 you list is certainly low voltage.... but it isn't that fast anymore compared to Intel.
I'd also recommend replacing the CPU heatsink/fan.. after the video card fan, it's often the loudest fan in a PC. Something like
this is going to be much quieter than the stock heatsink/fan.