PHP4 binaries with MySQL support?

Hi, I downloaded the binary for php4 with mysql support built in, but I couldn't find php_mysql.dll. I did find php_mssql70.dll, but can I really use that one? I downloaded the mysql server from www.mysql.com and installed it in c:\mysql (by default, and I haven't moved it. It seems to work allright as well). Now, as far as I understand, I need to configure two things in the php.ini-file: extension_dir = "path/to/my/module-dlls", and then extension = "module.dll". So, I want to put the php_mysql.dll here, right? But it's not to be found! Is it enough to put the right dll in my extension_dir as shown above? Another question: Is it possible to have more than one extension_dir declared? P.S. I'm using win98, Apache 1.3.12 and PHP4. Thanks!