[Mitch Ives]"1) Is anyone using that card in a MacPro?"
[Mitch Ives]"2) How long have you been using it in your MacPro?"
About 2 months. No issues here.
This is a pretty fast GPU and if you're considering running the updaded pro apps included with Final Cut Studio 2, Apple's website is (highly) recommending that the X1900XT be used for graphic intensive programs like Motion 3 and Color.
"Please take a moment to fill out your profile, including your computer system and relevant software. Help us help you."
I just put one in my Mac Pro (replacing the Nvidia 7300). It works and looks great...except...it's having trouble with HD material through my Matrox MXO in FCP only...not with Quicktime or anything else. Matrox is sending me a replacement unit, so hopefully it's that.