2003 networking optimization

Hello, i am stuck with setting tcpwindowsize, maybe someone may help:
i got a windows 2003 enterprise server connected to a linux system, without
a switch,

in dynamic link aggregation mode using the intel teaming driver, 2x1gbit
lets say for

failsafe reasons.
i can receive data with 900mbit, but can only send it with 500mbit - it
seems up to

the tcpwindowsize because iperf can do 900mbit with a windowsize of 64k.
i set the value "TcpWindowSize"=dword:00010000 within

HKLM\SYS\CCC\Services\tcpip\parameters
and for the teaming adapter

HKLM\SYS\CCC\Services\tcpip\parameters\interfaces\ <adapterUUID>
but it wont work.
i also tried to enable Windowscaling
"Tcp1323Opts"=dword:00000003
"GlobalMaxTcpWindowSize"=dword:00080000
and my linux system supports this, it doesnt work also.

maybe i missed something ?