there are no video card options with these machines - they only have a single video card slot - there are no pci-x cards.

you will be lucky to find even a replacement card - almost everything in this generation mac is hard to get - or obsolete.

you can try the matrox dual head and triple head to go - but you are pushing things a little.

as there was no possibility to have 3 outputs ( and there still isnt a workable solution ) you cant see the catalyst interface and have 2 outputs at the same time-

v4 design changed and nothing useful is shown in non-full screen mode - and there is more support for using matrox dual and triple head.