Determining browser type

Question

In my application there is some functionality that I want to disable if the user is using firefox. So I've put the button inside an if statement that checks to make sure the browser is greater then or equal to ie 5.5. This works fine. Now in my action class there is some generic code that runs for all screens.. (in my baseAction class) some of it needs to not fire if the browser is not ie. So I've put a c:set inside the if statement so that in thoery the variable will only exist in the session if I'm using IE.
So I ran a test.. the button does not appear but the variable does exist is session? Can anyone explain this to me?
And yes I realize I left out the ! in the check for browser.. but when I had it in the preview wasn't showing it (I'm using firefox.)
<c:if test="${OmniMgrApplicationConfig.vbaConfig.enabled}">
<--[if gte IE 5.5]><BUTTON name="button" type="button" class="OmniHeaderButton" title="VBATLMMenu" onClick="window.location='<c:out value='${pageContext.request.contextPath}'/>/jsp/TLMMenu.jsp'"
     onMouseOver="CLImage.src='<c:out value='${pageContext.request.contextPath}'/>/images/omniManager/shadow/form_green.png';"
     onMouseOut="CLImage.src='<c:out value='${pageContext.request.contextPath}'/>/images/omniManager/plain/form_green.png';">
     <IMG ALIGN="MIDDLE" src="<c:out value='${pageContext.request.contextPath}'/>/images/omniManager/plain/form_green.png" name="CLImage">
</BUTTON><c:set var="ieBrowser" value="1" scope="session"/><![endif]-->     
</c:

Answer 1

Not 100% sure since it is not a part of the app I am writing.. but the user has the ability to write scripts that will prepopulate the form. (writen in basically VBA)
This is all done through a Browser Helper object which I don't believe will run on firefox?
We have some clients that have scripts that are hundreds and thousands of lines long... we can't just say, by the way you can't use these. Of course we are writing a normal web gui that will do the same thing.. but some clients aren't going to want to convert all thier VBA.. plus they have employees that all they do is upkeep the VBA.