I have a general solution.
I had major slow uploads and downloads with FTP using Flash FXP
I used latest evox 1.4.3285, upgraded HDD to 80gig IBM, had 100/full dup etc etc.
I got on average 720kb for PC to XBOX and if I did the right mouse button trick it would reach maybe 3meg per sec if lucky.
So with the above taken into mind and not changing anything but the FTP program, I now get max 13meg per sec. for large files obviously, and the small ones ( i.e. .wavs) well need I say no more.
Program I use is webdrive. You use it by mapping a drive in explorer, and then hey presto, there is nothing better, I have tried the lot, and nothing comes close.
Lee