limited ethernet upload rate

[schorfi]

i have
an ASUS-M2V with Attansic gigabit lanchip (L1)
- gentoo 2.6.16 (r13)
- x86-64 architecture
my problem is that i want to send files to my friends in a switch 100mbit LANetwork, but it looks like that i cannot send many kb/s...
a download (upload for me) seems to converging to around 5-6kb/s and aborting after some time (mostly from my webserver)
i tried different uploads
-simple access via http-server (mini_httpt)
-ssh copy (scp)
-also sending functions from various programs
all seems to have the same problems

i was using the provided drivers from attansic (GPL) (0.1.40)
and now also a revised version from some kernel developer
(ftp://hogchain.net/pub/linux/m2v/attansic/kernel_driver/)
i just got the 2.0.0 running, others failed while compiling
i got a usual connection to the LAN network everythings seems to be fine even the download speed seems to be ok at least it is not a 5kb/s limit
i really wonder what the reason can be, i have no idea how to debug that problem and/or couldnt find any similar problems.. which indicates that the error must be located in front of this computer however maybe someone can help me? i'd be very happy
in addition the connectioncable seems not to be hurt as under windows everything works fine :-S
not sure if it is hardware problem even if the hardware is not the best

i doubt that there is a simple file restricting the bandwidth but i cannot excluded it...
i believe there is a problem with the amd64 architecture or another running program blocking the networt (but even if why just the upload?)
it looks like i have no idea...and yes i have
so i hope someone can help me with debugging (i tried ethtool a little bit but i am low on experience so i have no idea if some of the values are wrong or cause the problem described above)

thanks in advance

regards
schorfi