php mail not working on win98

I am getting this error on win98:

Warning: mail() [function.mail]: Failed to connect to mailserver at
"localhost" port 25, verify your "SMTP" and "smtp_port" setting in php.ini
or use ini_set() in

I have amended local smtp host in php.ini to that of my isp but getting
the same errors I am using php 5, apache 2.0.59 and mysql 4.1, is there a
solution to this php mail error in windows?