Can not detect IE8 using navigator.appVersion

Hello,
I'm developing a website and I need to detect what browser / version is being used. I'm using a javascript that I found at;
http://www.quirksmode.org/js/detect.html
When I run the website from Visual Studio (localhost), everything works perfectly. It detects IE8, Firefox 3.6.13, and Chrome 9.
My problem is when I deploy the site to our test site (a Windows Server 2008 R2 running IIS7 server), navigator.appVersion is returning
"Mozilla/4.0 (compatible; MSIE 7.0;..." when viewed using IE8!
In my .aspx code, I've added
<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE8" /> in the head section on every page. My IE Developer Toolbar confirms that default document mode is IE8, so why does navigator.appVersion return MSIE 7.0???

Thanks,
...