WL500g with WL330g

I´ve some problems with the transferrate ive got currently.
Ive hooked up a wl330g to my xbox (in ethernet adapter mode :)), installation went flawless.
But when i transfer a file from my laptop with builtin 54g adapter (which normally function very speedy) i only get 700k/s, which is kinda slow.
Does anyone has an idea how i can speed it up?

Config:
WL500g with WPA/WEP disabled, only MAC access control.
Only one wall between the wl500g and wl330g. (laptops with wlan transfer very fast at the same place)

btw: fast for me is around 4mb/s :D