I tried a few of these things until I got one to work in both Firefox and IE. This is what I came up with.
$("#my-Select").val($("#my-Select" + " option").filter(function() { return this.text == myText }).val());
another way of writing it in a more readable fasion:
var valofText = $("#my-Select" + " option").filter(function() {
return this.text == myText
}).val();
$(ElementID).val(valofText);
Pseudocode:
$("#my-Select").val( getValOfText( myText ) );