在本地为什么不能访问mysql?

我在本地机子上装了mysql5.0可是我去访问数据库时却提示我:"
Client does not support authentication protocol requested by server; consider upgrading MySQL client in c:\inetpub\wwwroot\test.php on line 4
Could not connect: Client does not support authentication protocol requested by server; consider upgrading MySQL client"
不知道是什么原因？那位高手帮忙看一下了，先谢谢了！！