如何在php 2.5.10和windows server 2008 + SQLserver 2008中安装mssql.dll驱动程序

I have configuration like this:

1. Windows Server 2008
2. PHP v 2.5.10.
3. SQL database 2008
4. Zend Framework v. 1.0.1 (2005r.)

I have download drivers to connect to MSSQL database and the connect is fine. The problem is with mssql.dll driver, because I have installed this driver and declared it in php.info but it's still not visible in php.info(). So I get the message: "The mssql driver is not currently installed" in my application.

In windows server 2003, MSSQL 2005, PHP 2.5.10 problem doesn't exist. I don't know how to solve this problem. Any idea?