Who is your web host ?
The reason I ask it that some hosts prefer you to use existing email scripts and those that they prefer you to use support multiple forms and multiple recipients.
For example, 1&1 prefer you to use a variant of Matt's FormMail script in PHP. This is for a number of reasons, not least of which are just how capable this is as a form handler and also that they are quite confident in its overall security.
It is fairly easy to set up and allows you to specify one or more forms and recipients on your site; you can set it up to send the results of form X to one recipient of your choice while form Y could be sent to any number of named recipients and an autoresponse can be triggered to reply to the form sender.
I can write PHP until the cows come home, but for most users I normally suggest something like this as a preconfigured script - no point reinventing the wheel if you don't have to. You fill in a few fields in the script itslef with your domain, host, recipient email address or addresses and any autoresponses you want and off you go.
No disrespect intended to the help you have had so far, but you may want to check with your web host about running various scripts. While they won't often physically prevent you from running your own PHP forms they may prefer you to use alternate means, for security reasons if nothing else, and you often find that, like 1&1, the script they suggest will handle as many forms on your site as you like and can also deal with multiple recipients and autoresponses.
Just a thought.