The Samsung 24" should have worked fine with the X850 card. Or even older cards. If the problem was panel noise then you have a checkbox in the Displays control panel (not at a Windows box right now so I can't tell you which tab it's on). The option toggles DVI support between coherent and non-coherent displays (difference between TMDS receivers made by Silicon Image and Texas Instruments).

And as Tom mentioned, the Mac Mini will work fine with the 23" Cinema Display.

Bruno