Most of you using instant messaging are probably using Windows Messenger 5.1. A few of you may be using MSN Messenger. Those who've already updated to the Windows Vista operating system are using Windows Live Messenger.
Windows Live Messenger replaces both previous Messenger products and is the only compatible version for Windows Vista. If you want to communicate via voice or video with Windows Live Messenger users, you'll want to upgrade to Windows Live Messenger.
To upgrade, go to Windows Live Services and click on 'Get it Free'.
On Windows XP, you'll need to be logged in as Administrator to install.