testing SMTP Mail send on windows

Hi I am very new to PHP and have just taken over our PHP website. This site was running perfect on linux but is now hosted on windows - IIS 5 (which is what I am currently testing on ). The one thing I cannot get to work is sending the "enquiries form" via SMTP. I have amended the PHP.INI file in windows and ensured the SMTP server is specified. This was set to just local host but I also tried the ip address of the server and also FQDN of the server ie: lon-dev-web.london.stemcor.com but still no luck. The SMTP service is running on the server as I can send an email via outlook express and also using telnet. I have created a simple PHP script to test the sending of mail: <?php mail("kimrichards76@yahoo.co.uk", "Enquiry response from Stemcor Site", "testing", "From: Kimrichards76@yaho.co.uk"); ?> I am just involing this in my browser to test it and have also run the script using DzSoft PHP editor but no result. Is there a way I can send some results to the screen when runnign the script which may help me find out what the problem is or where the problem is? At present I just get a blank screen and I am not clear as how to pass values to the screen at runtime. Alternatively does anyone have any suggestions as to other things I should set / check to get this to work. Many Thanks Kim