ATI AIW 9800 PRO, multiple video card support?

I found several people having difficulty running ATI AIW 9800 card
with another PCI graphics card, and no resolution. Has anyone got this
working??? This has been the most frustrating experience since Diamond
graphics card.

Background:
- Before I had ATI card, I had nVidia GeForce 4 (AGP), and MATROX
Millenium (PCI). They were getting alone fine, until I 'upgraded'
nVidia card to ATI. Symptom is as follows:

- upon installing the driver, the machine freezes (I have to do a
cold-reboot)
-> fine, so I manually installed drivers (by going through
Add/Remove hardwares and pointing to proper INF files)
-> now when I try to install Media Center, again it freezes!
(without this, I won't be able to use TV tuner... am I right?)
-> So manually installing drivers is not an option

- took PCI card out, and installed drivers, and accompanying software
-> everything installs flawlessly
-> after everything is installed, I put PCI card back in, boot ->
boots fine, both cards work fine, EXCEPT
-> upon start up, ATI control panel throws an error message (GPF)
-> In Display properties, click advanced button, and every time I
click any ATI tabs, GPF's again (not surprising, since ATI control
panel failed to start)

I also tried reinstalling WIndows XP without success. Has anyone
successfully made two video cards working?

Gabe