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 memory structure issue on glReadPixels() call.

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. 

Must have HP zx1 AGP GART driver installed.

Note: These drivers are only for Windows XP 64-bit edition.