It may "look" like ADC but may actually be DVI.

The two are very similar but not compatible.

These are the specs for the 20" Cinema Display
System Requirements

20-inch Cinema and 23-inch Cinema HD Displays

- Power Mac G4 or G5 with NVIDIA graphics card or ATI Radeon 7500 or better graphics card and Mac OS X v10.2.8 or later
- PowerBook G4 with DVI port and Mac OS X v10.2.8 or later
- Mac mini
- MacBook Pro with Mac OS X 10.4.4 or later
- iMac with Intel Core Duo and Mac OS X 10.4.4 or later
- Mac Pro
- Windows PC and graphics card that supports DVI ports with full single-link digital bandwidth and VESA DDC standard for plug and play setup

Note that the connector is described as a DVI connector and that with the correct video card in a PC, it will work.

All you need now is the Video card for the PC.

On the subject of Macs and the Government, you will be surprised just how many Mac's there are out there in Government land. They are beginning to learn just how secure they can make them.

Good luck

P