here's my experience with this mess:
I installed Civ IV, and it kept crashing on startup. I tried pretty much every suggestion I could find on the forums. Firaxis claims that the new drivers should work, however, so I decided to believe them and take the most drastic measure - a complete reinstall of Windows.
I wiped my hard drive clean, so that there could not possibly be anything left over from old driver installations. I installed Windows. Then, I installed my sound card drivers, then the 5.10 Catalyst drivers. I ran the Direct X installer on the Civ4 cd, and that installed fine. Finally, I installed Civ4. I rebooted between the install of each piece of software. Civ4 still does not run. Firaxis obviously seriously dropped the ball on this and didn't do nearly enough testing of different hardware configurations for this game. I am returning the game today.
By the way, my video card is a Radeon 9800 Pro 128 Mb.
-Jared