Always embarassing to reply to oneself...But...
What my previous post meant is that with the above mentionned 7600 GS cards, it is probably not necessary to worry about aftermarket coolers.
Now what I would like to find are web reviews of the BFG, MSI or Leadtek fanned 7600 GS cards listed above, to confirm that they operate quietly at low temperatures. Anybody found such a review?
For the 7600 GT, most manufacturers seem to simply be affixing their sticker to the reference cooler, but I have found a few exceptions (Leadtek, MSI, passive Asus and Gigabyte).
The question of finding a powerful, silent, low-profile replacement for the reference cooler seems most pertinent for the 7600 GT.