samba - Aug 2008 - Samba performance copying files to windows too slow

Hello to all,
I have a problem when copying files from my shares on samba3.031
(Suse10.2) to win-xp clients.
The transfer is extremly slow.
My smb.conf:
[global]
Read raw=yes
Write raw=yes
Socket options=TCP_NODELAY IPTOS_LOWDELAY

I tried SO_RCVBUF and SO_SNDBUF this made transfer impossible
and so did max xmit too.

Can You help me?

Greetings
Daniel