samba - May 2005 - XP domain join troubles - is it XP or Samba issue?

In order to join an XP machine to a Samba domain, one has to change sign 
and seal registry entries on an XP machine, at least this is what you 
can find on the web.

On the other hand, I'm pretty sure I've read in Samba Guide, that 
changing sign and seal on a Windows XP machine is not needed at all - 
what you need, is a correct Samba smb.conf setup:

http://us2.samba.org/samba/docs/man/Samba-Guide/kerberos.html

"Sign'n'seal (plus schannel support) has been implemented in
Samba-3."


To sum up, we have two approaches:

1) one has to change XP settings, otherwise won't join
2) one can set up Samba correctly, and not touch any XP registry, and 
join an XP to the domain.


So, which one is true for XP domain joins?

I can't set it up to work without registry hacks, even though, according 
to official smb.conf man:

Default: server schannel = auto

So theoretically, it should work out of the box?

So why it doesn't?

I'm running Samba 3.0.14a.

Tomek