Here's one approach:
Put all three drop-downs in the same form; set them as illustrated below. When the user changes any select, Select.onchange is called, invoking chkredir(), and passing references to all three Select objects.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>untitled</title>
<script type="text/javascript" language="javascript">
// redirect URLS here, keyed to combinations of selected indexes
var URLs = Object();
URLs['111'] = 'http://www.google.com';
URLs['211'] = 'http://www.altavista.com';
URLs['311'] = 'http://www.hotbot.com';
function chkredir(oSelect1,oSelect2,oSelect3) {
var sOpts;
var s1idx = oSelect1.selectedIndex;
var s2idx = oSelect2.selectedIndex;
var s3idx = oSelect3.selectedIndex;
if (!s1idx || !s2idx || !s3idx) return false;
else sOpts = String(s1idx) + String(s2idx) + String(s3idx);
alert(oSelect1[s1idx].value + '\n' + oSelect2[s2idx].value + '\n' + oSelect3[s3idx].value); //demo
if (URLs[sOpts]) frames['movies'].location = URLs[sOpts];
}
</script>
</head>
<body>
<div align="center">
<form>
<select name="Attention" onchange="chkredir(this,Mood,Motivation)">
<option>Attention Span</option>
<option value="3 mins">3 mins</option>
<option value="5 mins">5 mins</option>
<option value="10 mins">10 mins</option>
</select>
<select name="Mood" onchange="chkredir(Attention,this,Motivation)">
<option>Mood</option>
<option value="Stressed">Stressed</option>
<option value="Happy">Happy</option>
<option value="Bored">Bored</option>
</select>
<select name="Motivation" onchange="chkredir(Attention,Mood,this)">
<option>Motivation</option>
<option value="Active">Active</option>
<option value="Semi-active">Semi-active</option>
<option value="Passive">Passive</option>
</select>
</form>
<iframe name="movies" width="700" height="400"></iframe>
</div>
</body>
</html>
The function gets the selectedIndex property - the integer representing which option has been selected (JS counts from 0, so the 'dummy' options are all option 0). It checks to see if any of them is zero - zero is synonymous with false in JS so, the not operator (!) 'flips' any 0 to true and the function terminates. Otherwise, we're good to go; the next line is a demo (remove it); all that's left is to check for a URL (stored as a property of the URLs object) and load it if found. I used an iframe, typical for swfs; change to simply location = if you want to redirect the entire window.
Hope it works! cbp