You need the latest version of the FastATA software, otherwise HDDs bigger than 136GB won't work. Also more then 136GB won't work on the internal IDE bus (if you ever choose to remove the FastATA).
As the FastATA software is loaded from disk you probably are not able to boot from a partition which crosses the 136GB border. (I am not even sure if you are able to boot from a partition which is outside the first 4GB of the drive).
And of course you need a file system which uses 64bit commands (e.g. SFS, PFS3, FFS V43+).
Bye,
Thomas