Hey there,
I too have bought the Firewire 1814. I also had a lot of difficulties with it. I searched and searched for answers. THIS IS NOT A SIMPLE "PLUG AND PLAY"
-1st thing is first, I see that you have downloaded the latest drivers (BETA 1.8.4-3) from the website. Thats a MUST.
-The next thing is to go to this link which will lead you to a page from an M-Audio tech that explains a clean installation of the drivers.
http://forums.m-audio.com/showthread.php?t=776&highlight=firewire+1814
REMEMBER TO FOLLOW DIRECTIONS EXACTLY - I was skeptical about all the "Repair disk permissions", however, these M-Audio Techs get paid a lot of money to sit at a computer and solve problems, so I just decided to sit through the 4 times it takes and listen to them.
-After you know you have installed it correctly you can start looking at other problems.
I noticed that this interface has a lot of features I do not need. (however I got it for 200$ brand new so I am not going to return it)
I am going to try and explain JUST THE BASICS which will allow you to record your guitar.(it took me a while...and the manual is not really a help unless you have a degree in this stuff or a lot of experience) Everything else about this interface I can not help you at this time because I too am learning everything about this.
Make sure that the firewire cord is plugged into #1 in the back of it.
In logic, check in the prefrences to see if the primary input and output are set to the Firewire 1814. I belive you may have the option of "Stereo 1/2", I picked that one.
Make sure that you are making a New Track with a "Real Instrument" and for the input make sure you select the "Firewire 1814 Stereo 1/2"
By now you may be able to see some sort of Green showing that the instrument is playing.
This will at least let you record. Most likely you will have a problem with playback. I found using a stereo with stereo inputs, that I had to get an adapter to merge the inputs to a 1/4" output. This 1/4" stereo output must be plugged into the back of the interface. I plugged it into output #1. I am trying to figure out how to have the Red and White outputs work. But for now I am just using a 1/8" to 1/4" adapter plugged in the back.
You may also want to try fooling around with the Firewire 1814 Control Panel which can be found in the "System Preferences" all the way at the bottom.
If you feel that it is something else you may want to try calling them.
Hope this helps enough. I was so frustrated that I was thinking of downgrading from Leopard just to make it possible to record.
Good Luck