Hi gedescamps,
I had a similar problem using MD5. Only when I couldn't log into my CP did I realise there were more changes...
There are 3 files to change:
member.php (lost password, logon, etc.)
register.php (initial registration)
admin/sessions.php (for passwords into CP)
Also see:
http://www.vbulletin.com/forum/showt...threadid=23957 (A hack I released covering MD5 encrypted passwords)