Piece of cake. Click here to go to the installation page for the Yahoo! Messenger for Vista Preview.

Note: Download can take anywhere from 1 to 15 minutes. You need 40MB of free space to install Yahoo! Messenger.

After installing it, launch Yahoo! Messenger. If you already have a Yahoo! ID and password (the same one you use for Yahoo! Mail or any other Yahoo! site), you can sign in with that. If you don’t have an ID yet or you want to create a new one, click Get a new Yahoo! ID to create a free Yahoo! account.