dual-monitor display problem

Hello,

I purchased a MD-219 http://maxdisplays.com/x.php?md-219
.
I want to hook up both a Dell PC and a Mac G5 to this monitor
and be able to run them at the same time(one display to a computer/2 displays to a computer). I was told by someone that it was possible to do this by running one machine on the digital inputs and another on the analog inputs and then...source between them???.Im not sure what that means?

Also,in the manual they recomend using a "Quadro4 200/280 NVS,Quadro4 400 NVS and Quadro4 550/580 XGL".The Quadro4 200 and 400 NVS PCI must be inserted into a PCI slot(wich makes sense)All other Quadro cards are AGP cards.So what are the differences between PCI and AGP?Wich graphics card should I go with?Will any of these multi-port video cards also work with my Mac G5?If not?..what could you recomend?

what does this mean below?

The online manual says this:

"Max Displays monitors (excluding the MD-215 which can run on two common
15 pin analog VGA D-Sub signals) require a separate DVI signal for each
screen. This means that you will need a video card that supports multiple
DVI output.

Note: VGA to DVI adapters will not work with Max Displays monitors. This
means that if your video card has one DVI port and one VGA port, you will
not be able to use the VGA port."

what does this mean???



If you could help me make my selection so i can get my new monitors up
and running it would be greatly appreciated.I hope this is enough information.

Thank you for your time!

-n