I've got a passive heatsink card, and for most low end stuff they probably work fine. I started having issues about 6 months into mine. Finally ended up pulling the card, removing the heatsink. Removed the pink gunk they put in there, reset the heat sink with Artic Silver, then put a 9" 110v 2 speed fan in front of the open case.
No more heat issues. Low speed for winter, high for summer. And no its probably not quieter than a 80mm fan on a video card. But its not obtrusive either, and it doesn't draw power from my power supply.
Would I recomend one? not for gaming, not unless your willing to do what I did.
Now the wife's machine has the same card and she gets along fine. But she doesn't fly or do high end gaming.