samba - Jun 2004 - Migration from 2.2.x to 3 : Any known problems ?

Hi,

I have a samba 2.2.7 server that I plan to move to a new one with the 3.0.X.

I was wondering if there are any changes in the conf file or other
necessary files (such as smbusers/passwd) that I should be aware to
avoid problems.

No facny setup, standard 2.2.7 configuration with a couple of shares. 
No printer no BDC etc.