Well I don't currently have access to all of the details but from the sounds of it your system is running the the ballpark mine is. I'll try to give better details later but for now I'll suggest this.

Go to Start -> Run
Type: regedit
Go to: My Computer/HKEY_LOCAL_MACHINE/SOFTWARE/PlayOnlineUS/SquareEnix/FinalFantasyXI

Each of the Values here applies to something specific in game. For instance I believe 0000 is the MIP mapping one. Now from FFXI Config you can't do much with this but here you can kinda crank it up. You'll probably have to play around to see where you like it and where your computer can handle it but 0 is off... when you are around 6 things will look quite blurred but nice. Basically it's giving you pseudo-antialiasing. I like running mine around 4 personally.

0001
0002

This affect your resolution. I personally like 1280x1024. To get this set 0001 to 500 and 0002 to 400

0003
0004

This is where you can really crank things up and make it look really nice. 1024x1024 would have both values set at 400. Raising them incrementally (and at the same value) will make things look increasingly sharp. I'm not sure if going over 800 would be a good idea. That will set you and 2048x2048 and will look really really nice.

I've forgotten several of the others off the top of my head like Bump Mapping and stuff but as soon as I find the details I'll try to post them.