samba - Apr 2005 - very slow writes from samba client to samba server

I'm running Fedora Core 3 on two machines; a server and a client. On
the server, I have the package samba-3.0.10-1.fc3 installed; I assume
this means I have samba version 3.0.10. On the client, I have
samba-client-3.0.10-1.fc3, i.e., the same version.

On the same network, I have a Windows XP home machine that connects to
the same shares as the FC3 client machine.

Reading and writing files on the WinXP machine to and from the server
works perfectly. Reading files stored on the server from the FC3
client machine also works fine. But when I try to write files from FC3
client to FC3 server, it takes a very long time. Extremely long, like
< 1mbit/s, and this is a 100mbit/s network. Actually, it takes so long
that for a file of any real size (1Mb+) the copy/save errors out
before the writing is done.

I have googled this issue, and written to fedora-list, but nothing is
helping so far. All the advice suggests that this is a master-browser
collision problem. So I edited my smb.conf files accordingly (setting
the os_level, etc. lower in the client), but that didn't help. Here
are my smb.conf files anyway, just in case I've done something wrong.

On the server (I've removed all commented lines for brevity):
-----
[global]
   workgroup = CONCRETE
   netbios name = ONE
   server string = Samba Server
   hosts allow = 192.168.1. 127.
   printcap name = /etc/printcap
   load printers = yes
cups options = raw
 log file = /var/log/samba/%m.log
   max log size = 50
   security = user
  encrypt passwords = yes
  smb passwd file = /etc/samba/smbpasswd
   create mask = 0644
   directory mask = 0755
   socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192
   local master = yes
   os level = 33
   domain master = yes 
   preferred master = yes
   wins support = yes
   dns proxy = no 
   idmap uid = 16777216-33554431
   idmap gid = 16777216-33554431
   template shell = /bin/false
   winbind use default domain = no
[homes]
   comment = Home Directories
   browseable = no
   writable = yes
[printers]
   comment = All Printers
   path = /var/spool/samba
   browseable = no
   guest ok = no
   writable = no
   printable = yes
[Music]
   comment = Music
   path = /home/music
   public = yes
   read only = no
   valid users = amy matt
   writable = yes
   create mask = 666
   directory mask = 777
   guest ok = no
------
And on the client:
-------
[global]
   workgroup = CONCRETE
   netbios name = MATT
   server string = Samba Server
   printcap name = /etc/printcap
   load printers = yes
cups options = raw
 log file = /var/log/samba/%m.log
   max log size = 50
   security = user
   socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192
   local master = no
   os level = 3
   domain master = no 
   preferred master = no
 name resolve order = wins lmhosts bcast
   wins server = 192.168.1.1
   dns proxy = no 
   idmap uid = 16777216-33554431
   idmap gid = 16777216-33554431
   template shell = /bin/false
   winbind use default domain = no
-----
Any advice? 

Thanks a lot,
Matt