It doesn't matter, all servers are located in Japan. In addition, SE has capped data transfer speed at 56k/sec, so even if you had an entire pipe to yourself, you wouldn't download any data faster than a dial up modem using a 10 year old AOL free trial disk.
Honestly, ping has very little to do with game play in FFXI. The focus of the game is teamwork, not button work; ping between you and the server will not effect how fast the monster you're fighting dies.
The only time network latency is an issue is when you are in areas crowded with monsters or players, such as the AH in Whitegate or inside of Besieged. If you experience slow graphics outside of crowded areas, I would suggest turning down your graphic settings; turning off weather effects and shadows goes a long way towards speeding up frame rate.