[Samba] Slow copy from windows

[Facundo Russo]

Samba 3.6.3-23.2.0-41-generic-paeUbuntu 12.04Realtek 8111B
Whenever I try to copy a file to a samba share from windows 7 or xp machine the copy is too slowaround 800-1000 KBps8FTP or SCP works 10 times faster
also when copying from the share to my PC it also goes fast
the problem occurs only when copying files to the samba share
tried changing the NIC and the problem persist
here is my smb.conf i've skipped shares for readability
[global]workgroup = HACIENDA_SALTAnetbios name = procuracionrealm = salta02.localpassword server = salta02.salta02.localpreferred master = noserver string = Files Serversecurity = ADSencrypt passwords = truelog level = 2 vfs:2log file = /var/log/samba/%U.%m.logmax log size = 10000syslog = 0
lanman auth = yesclient lanman auth = yesclient plaintext auth = yes
name resolve order = wins lmhosts hosts

strict sync = yessync always = yeskernel change notify = yesdns proxy = no
acl map full control = yesacl check permissions = Truewinbind enum users = Yeswinbind enum groups = Yeswinbind use default domain = Yeswinbind separator = /preserve case = Yesshort preserve case = Yescase sensitive = noidmap uid = 11000-13000idmap gid = 11000-13000template shell = /bin/nologintemplate homedir = /files2/muni/homes/%D/%Udomain master = nousername map = /etc/samba/smbusers
hosts allow = 172.16. 10.0.100. 10.0.101. 10.0.102. 127.interfaces = lo eth0 x.x.x.x/16
max smbd processes = 300usershare max shares = 100panic action = /usr/share/samba/panic-action %d
load printers = no