mysql_connect !!!!!!

[Phuong Phan]

Hi, i have a trouble like this

mysql_connect(): Client does not support authentication protocol requested by server; consider upgrading MySQL client

phpinfo: Client API version 3.23.49
mysql: MySQL 4.1.9-nt

with mysql like above, what is the minimum requirement of php i must have to use common functions of php? I written some code in php 4.*, so that i don't want to change to php5. If i change to use php5, i have to rewrite some code, right?

I need your advices......

Thanks a lot.
(mail me @ [e-mail])