Nexfan carries the Zalmans at a good price. I can vouch for them being very quiet, and beefy, not a flyweight overspec'd item at all.
Servercases has the Seasonics at the same price, haven't tried them myself, but their reputation is good, supposedly even quieter than the zalmans.
If you feel that more power is required, then spending considerably more for a Tru-Antec would probably be the way to go.
You're off to a good start. Now you just have to avoid whiney chipset and vidcard fans, make the right cpu hsf choices along with quiet case fans and HDD's. It's not easy, modern systems pour out heat like crazy....