Who is your ISP? This information should be readily available from their support site. And, again, here's the snippet you need to look for in your PHP.INI file...
[mail function]
; For Win32 only.
SMTP = smtp.west.cox.net
smtp_port = 25
; For Win32 only.
sendmail_from = myemail@cox.net
I removed my e-mail for security reasons but that way you can get the idea.
To benracer:
Ben, he's not using a hosting company. He's using Xampp on Windows from his home internet connection. I've got it working the same way he's trying to.