I can sustain a consistent 22Mbps to the xbox and 85Mbps up from the Xbox to the PC. I have been trying to figure out some of the problems people are having for a few days now. So far I have come to the following conclusions.
1: The Quality of the NIC "DOES" matter. I have tested el cheapo MPX, Linksys, Realtek and some others and I have found that my 3COM blows them all out of the water.
2: The difference between a hub and switch matters as well. I have tested both and found that the sitch gives a faster upload/download. Also, to alleviate it altogether just use a crossover cable direct from the NIC you are using to transfer Data.
3: and heres the real sticker I can't figure out. I have noticed that if any of my other PC's (I have 3 on a switch) are downloading anything from the internet (Except for the server) then transfer speeds drop down, way down! low. 100-500K.
4: FlashFXP and Smart FTP work at the same speed up and down with all NC cards tested.
Thats about it. Hope it helps.