I use to have that exact system, great computer...
I am currently running 2 DVI monitors that are 1600x1200 a pop. I am running the ATI Radeon 9600 (I am pretty sure). It has one ADC port and one DVI port. The DVI port in the back of the system is DVI-I (meaning that it carries both an analog and digital signal). The new Apple displays should be DVI-D displays, therefore it is possible that they will work with any ADC to DVI converter. However, I experienced problems with all of the converters except for the DVI Extractor II by Dr. Bott.http://drbott.com/prod/db.lasso?code=0123-ADE2
So, if I am not mistaken the Video card that is in your computer has one ADC and one DVI port, correct? If this is the case, you should be able to just purchase the DVI Extractor II, run that from the ADC port to one of the LCDs. Then, just run the other one directly to the DVI port in the back of your video card as it is.
I hope this helps. Did I understand you correctly? :huh: