"you get what you pay for"
I know that Zalman has some GREAT products. I use their
cpu fan myself (7000B Cu) and is 100% satisfied. But they
aren't the cheapest...
If the card you're planning on buying is a Nvidia of some
new sort it could also be interesting to consider water-cooling
since Nvidia:s sound like vaccum-cleaners and you can move
the water-cooling system.
If planning on an ATI though I know that the ASUS X800-series
has a special extra large fan that is near dead silent. I know
this myself since I have one and the Chassi-fans sounds
more than the video-card! Oh - and those are Papst-
chassi-fans by the way.