gnarf

No IE Welcome can react to a Visitor using Microsoft IE (Internet Explorer) of a specified Version. You can
<ol>
<li>Slide Down a Infoscreen (changeable CSS Style) where the User is informed that he should update his browser. All Texts and update Links are defineable in admin menu. No Popup is used, so no chance fpr Popup blockers. You can define a time where the Infowindow hides again automatically.</li>
</ol>
and / or
<ol>
<li>You can use a different WordPress Theme for these users. It can be a Theme that is optmized for IE, or a Theme where you suggest the user to Update / Cange Browser and so on. </li>
</ol>
For Users not affected by the Plugin the source code is not changed. So the Plugin is highly performant and a non IE User doesnt notice the use of the plugin at all.
Easy Installation and configuration.
Also visit the <a href="http://wordpress.losmuchachos.at/no_ie_welcome" title="Plugin Page" rel="nofollow ugc">PluginPage</a>.

No IE Welcome

No IE Welcome allows you to inform Vistors of a specified IE Version to Update their Browser. Also a different Theme can be used for these Visitors.

Pierre-André Boissinot

Semio Design

This plugin detects if a visitor is using some old version of Internet Explorer and suggests to upgrade to a recent browser. 
The versions to block can be configured in an admin panel. 
Works for blocking IE6, IE7 and IE8. 
Localisation of the plugin into french.

Stop Oldies

This plugin detects if a visitor is using some old version of Internet Explorer and suggests to upgrade to a recent browser.

No IE Welcome vs Stop Oldies