http://msmvps.com/blogs/egoldin/archive/2007/05/21/detect-vista-on-client-machine.aspxIf you need to know if client&#39;s browser runs on a Vista machine, run javascript navigator.userAgent or navigator.appVersion and search the returning string for &quot;Windows NT 6.0&quot;. If it is there, you are on Vista.enCommunityServer 2008.5 SP2 (Build: 40407.4157)http://msmvps.com/blogs/egoldin/archive/2007/05/21/detect-vista-on-client-machine.aspx#1287805Thu, 08 Nov 2007 09:19:27 GMTd67277c4-116b-43f1-b688-e9ef184ea916:1287805Thomas Nordahl<p>Yup!</p> <p>navigator.userAgent returns a string that looks like this in my firefox (on win xp): &#39;mozilla/5.0 (windows; u; windows nt 5.1; da; rv:1.8.1.8) gecko/20071008 firefox/2.0.0.8&#39;</p> <p>(navigator.userAgent.toLowerCase().indexOf(&quot;windows nt 6.0&quot;) &gt; -1) will return true if the clients version of windows is vista.</p> <p>Will the version 6.0 change if there are service pack upgrades in the future?? perhaps you should only search for &#39;windows nt 6&#39;, so it will work if it changes to 6.1?</p> <div style="clear:both;"></div><img src="http://msmvps.com/aggbug.aspx?PostID=1287805" width="1" height="1">http://msmvps.com/blogs/egoldin/archive/2007/05/21/detect-vista-on-client-machine.aspx#1184191Mon, 10 Sep 2007 15:06:46 GMTd67277c4-116b-43f1-b688-e9ef184ea916:1184191Ulf Gleby<p>In Firefox, navigator.appVersion does not contain the string &quot;Windows NT 6.0&quot;. In IE it does.</p> <p>Check navigator.userAgent instead. It works for both Firefox and IE.</p> <div style="clear:both;"></div><img src="http://msmvps.com/aggbug.aspx?PostID=1184191" width="1" height="1">