Nvidia Legacy on Windows 7

I have the HP XW 8400 Workstation. Windows 7 Pro 64 bit 32GB memory.

After looking over HP recommendations from low end graphic card to high end graphic card I replaced the Nvidia Quadro FX 1500 with the Ndivia FX 3500.

The bios is updated on the Workstation.

With the FX 3500 I started with installing recommended drivers for Windows 7 – the 3D was a mess, I was unable to work on any browser and other difficulties. I then started getting BSODs with NVLDDMKM.sys message.

I removed that driver and started with HP’s recommended FX 3500 driver for Windows Vesta. The display area was awful with icons looking degraded – Adobe applications spluttering to start. The Nvidia control panel was in most areas unresponsive.

Device manager indicated the FX 3500 was working fine. I elected to attempt an upgrade from Nvideo 7.15.10 (12/19/2006). The upgrade bumped the card into ver 8.15.11 (5/14/2009). After the upgrade nothing changed to improve the graphic display, computer behavior. In fact the Nvidia control panel with the upgrade is not working.

I have this link showing several dozen Vista drivers for XW 8400 Ndivia FX 3500 drivers. Now it becomes an issue finding the most current, most useful driver that will work with this workstation without having BSODs over the NVLDDMKM.sys message.

I have another HP XW 8400 workstation with the FX 1500. That machine works perfectly.
I could replace the high end FX 3500 with a low end card but in that HP recommended the card I would think it should work – but I would need the best driver for this to happen.

Let me know if there is the obvious fix.
Thanks