[Samba] Samba and Window XP write performance

[Gustavo Rincon]

 did some testing using samba-3.0.0 as a server and two identical clients
one Running W2K and other running Win XP pro.
If I write a big file using the W2K client, I'm getting about 25 Mbytes/sec
but if I run the same testing using the Win XP Pro, this
client only is able to get 12.5 Mbytes/sec.  (The Server, clients are using
1000 Gbits NICs)

There is a problem between XP and samba?