I currently have a flashed HD4890 installed in my MP1,1. I have my original X1900 XT sitting somewhere collecting dust. Drawback is I can't enjoy a second screen in OSX which I started to miss very much. So I plan to try a new setup but I'm not really sure about few things, so anyone that knows better on the subject please enlighten me. Here it goes: Let's say I put the X1900 XT back in. Then connect it to my second monitor on a dvi port (it's already connected through hdmi on the HD4890). Then even CrossFire the cards together. 1) I understand that Crossfire doesn't work on OSX. That shouldn't prevent the cards to be used separately as normal though, would it? 2) In windows, would Crossfire work just like that (given that I install any needed drivers) or would I need to setup the cables differently (e.g SLI Y-shaped cables)? 3) Back in OSX, would the X1900 XT have a significant difference vs the HD4890 on video performance? Because it will mostly be used for movies. I never got that 'HD' thing anyway, the X1900 supports higher res than 'Full HD' and it's doable through a dvi cable, if you only want video and not sound. Also both cards have the 'Avivo' technology that I'm not really sure what that is but it's supposedly meant for HD video. So, any thoughts on this?