The FFXI website wrote:
ATI® Technologies (http://www.ati.com)
Compatibility has been confirmed for the following graphics cards using the "Catalyst 5.13" driver.
- RADEON X1800 series
- RADEON X1600 series
- RADEON X1300 series
- RADEON X850 series
- RADEON X800 series
- RADEON X700 series
- RADEON X600 series
- RADEON X300 series
- RADEON 9800 series
- RADEON 9700 series
- RADEON 9600 series
- RADEON 9500 series
- RADEON 9200 series
- RADEON 9000 series
* Compatibility tests are currently being conducted on other graphics hardware.
* The OS used for compatibility testing is Microsoft Windows 2000/XP
* Depending on your system's configuration, the above graphics cards and drivers may not function correctly. Acquiring and installing driver software is your responsibility.
* The above information is confirmed as of March 2006. Later drivers or graphics cards may not function correctly or be detected.
* If you are using a computer that was made by an OEM vendor, please use the graphics drivers provided by the manufacturer.
I have a Radeon card so I really can't help you there, I use the most current catalyst drivers for it and they work fine.