Make sure you got the right answer, because there's alot of people out there thinking they know the answer when they don't and they're usually the first in with the myth, not the truth.
Okay Great Grape, I was told that for me to have the three monitor display with my HD5850 video card, I have to use a active displayport to dvi and not a passive adapter.
If one isn't a VGA monitor then yes, but you can use a passive VGA adapter for the third monitor, but if all are DVI or all are HDMI then you need an active adapter.