The driver has been released by Hewlett-Packard for their workstation models zx2000 and zx6000 and according to the release notes you must have the HP zx1 AGP GART driver installed.
Supported Workstation Models: hp workstation zx2000 hp workstation zx6000
FIXES: - Fixes memory structure issue on glReadPixels() call.
KNOWN ISSUES: Issue: nVIDIA graphics do not display video during EFI boot when using a direct DVI connection on primary port.
Root cause: System firmware and video BIOS compatibility issue.
Workaround: Use analog input on primary port. Solution: HP and nVIDIA are working on a resolution. This solution may require both a firmware and a video BIOS update.
Issue: Dual-display instability using dual DVI inputs. Secondary DVI display will eventually go into a strobing mode. If a display refresh is attempted during this period, the monitor will clear to normal temporarily.
Root cause: Driver monitor synch issue with secondary DVI display.
Workaround: Use analog input on secondary port. Solution: Working with nVIDIA to provide an updated driver to correct this problem.
PREREQUISITES: Must have HP zx1 AGP GART driver installed.
Note: These drivers are only for Windows XP 64-bit edition.
Here's other similar drivers that are different versions or releases for different operating systems: