Just out of curiousity, I checked all the major MFG sites: NVIDIA, ATi, Matrox, 3dlabs. And none of them have a card that will do 2560x1920! Even this beast of a board
can't do it!
What monitor are you using? Unless it is a >30incher, I don't think anyone would need that resolution, especially if it is at 60Hz! Besides, your eyes might bleed from the beauty of it!
The closest thing would be the R300, aka Radeon 9700 Pro. ATi lists it as being able to do 85Hz @ 2048x1536.