Fotiman - 2:57 pm on Mar 12, 2013 (gmt 0)
Welcome to WebmasterWorld!
It looks like you're also using tables for layout, another no-no. Leave the presentation to CSS.
With that said...
If I understand you correctly, and what this code is attempting to do, you're referring to this textarea:
<textarea name="SI_Query_Box" id="SI_Query_Box" cols="15" rows="5" style="display:none" onKeyPress="return myKeyPress(event,'SI_Query_Box')">
If you want this to submit when enter is pressed as opposed to adding a new line in the textarea, then you should rethink whether a textarea is the correct element to use. Textareas are meant for multi-line text input, while a regular <input type="text"> is for single line values. If you change this to an input element, then pressing enter will trigger the default submit action (equivalent to clicking the first submit button in the form).